From Micro-Teaching to Classroom Teaching: An Examination of Prospective Mathematics Teachers’ Technology-Based Tasks

This study examines the changes and development of prospective secondary mathematics teachers‟ technologybased tasks through teaching practices. The Dynamic Geometry Task Analysis model consisting of the components of mathematical depth and technological action has been chosen as the conceptual framework of the study. In this study, a qualitative research paradigm has been adopted and action research methodology involving a cyclical process has been used. Participants of the study were four prospective secondary mathematics teachers, who were enrolled in a secondary mathematics education program at a state university in Turkey. This research was carried out within the scope of a 14-week Practicum course and focused on prospective mathematics teachers‟ implementations of their technology-based tasks through micro-teaching and classroom teaching. Data mainly consisted of each prospective teacher‟s one technology-based task, video recordings of their teaching practices (micro-teaching and classroom teaching) and interviews. Data was analyzed by using the video analysis method to examine how and why mathematical depth and technological action of the planned tasks changed or developed during micro-teaching and classroom practices. Findings of the study indicated that prospective mathematics teachers improved the levels of mathematical depth of their tasks by making use of their planned technological actions in a more effective way from micro-teaching to classroom teaching. In particular, it became apparent that microteaching supported the development of prospective mathematics teachers‟ technology-based tasks in terms of content and also the implementation processes of their tasks in classrooms.


Introduction
National curriculums and standards in many countries emphasize the importance of digital technologies on learning and teaching processes in mathematics education (National Council of Teachers of Mathematics [NCTM], 2000; National Center for Excellence in the Teaching of Mathematics [NCETM], 2014; Ministry of National Education (MNE), 2013; 2018). Accordingly, there are a number of research studies focusing on the integration of digital technologies into mathematics education in the related literature (e.g., Akyuz, 2016;Baki, 1996;Clark-Wilson, Robutti, & Sinclair 2014, Drijvers 2012, Erfjord, 2011Hollenbeck, Wray, & Fey, 2010). These studies indicate the positive effects of using digital technologies on enriching mathematics learning and teaching, developing students" mathematical thinking and understanding, and increasing students" motivation and interest in mathematics. Equally, the national and international literature underline the crucial role of teachers in incorporating technology effectively (e.g., Akkoç, 2012;Clark-Wilson, Robutti & Sinclair 2014;Yiğit Koyunkaya, 2017). In Turkey, in the document about Teacher Competencies published by the Turkish Education Association, one of the teacher competencies is pointed out as "an effective use of information technologies" (Teacher Competencies, 2009, p. 10). Similarly, "effective use of information and communication technologies in the teaching and learning processes" (General Competencies for Teaching Profession, 2017, p. 14) is highlighted as one of the teacher competencies. The word effective here indicates that teachers should not only have technological knowledge per se, but also consider using appropriate pedagogical techniques relevant to the class level and the topic taught in order to make a difference compared to using traditional methods. To integrate digital technologies into teaching effectively, teachers need "detailed road maps and also experts or teachers who can act as a compass" (Bozkurt & Cilavdaroğlu, 2011, p. 868). Detailed road maps can be defined as detailed lesson plans that teachers prepare beforehand. In this sense, teachers (practicing and prospective) aiming to use digital technologies in teaching should be supported in their preparation and development processes of lesson plans (Hur, Cullen, & Brush, 2010). In particular, prospective teachers should be provided with an environment, where they can prepare lessons with the use of digital technologies in their teacher education (Ozgun-Koca, Meagher, & Edwards, 2010).
In this light, researchers draw attention to the importance of "Practicum" courses in teacher education aiming to increase teaching experiences of prospective teachers with the integration of digital technologies into mathematics lessons. In this process, micro-teaching is regarded as an important and useful preparation tool for prospective teachers" teaching experiences in classrooms (Allen, 1980;Griffiths, 2016;. While prospective teachers could have an opportunity to experience classroom teaching to some extent in school placements, they may not experience all possible situations that may occur, hence micro-teaching could be a crucial step for them to experiment before their classroom practices (Ledger, Ersozlu & Fischetti, 2019).
Research indicates that digital technology integration in mathematics teaching has progressed much slower than expected (e.g., Clark-Wilson, Robutti, & Sinclair 2014). Similarly, in Turkey, despite the huge funds allocated for schools to provide suitable technology hardware and infrastructure, digital technologies could not be effectively integrated into mathematics teaching (Çiftçi, Taşkaya, & Alemdar, 2013;Kayaduman, Rowkaya, & Seferoğlu, 2011). When professional development programs are examined in Turkey, it become apparent that they mostly focus on the technical elements of technology rather than pedagogical and mathematical aspects, which those technologies could trigger (Uslu & Bümen, 2012;Pamuk, Çakır, Ergun, Yılmaz, & Ayas, 2013). Hence, in this study, in the context of a 14-week Practicum course at a Turkish University, we aim to support the professional development of four prospective mathematics teachers (PMTs) on technology integration by enabling them to learn how to effectively blend technology into their teaching. In particular, we focus on the processes where the PMTs integrate dynamic mathematics software -GeoGebra-to design technology-based mathematical tasks, to develop these tasks through micro-teaching and to practice their tasks effectively in classroom environments. The main goal of this study is therefore to examine changes and development of the PMTs" technology-based tasks on the implementation processes of micro-teaching and classroom teaching in school placements.

Conceptual Framework
Mathematical tasks are considered as one of the most important elements that support learning and teaching in classroom practices (Smith & Stein, 1998;Swan, 2007). Hence, we believe that it is of essential importance to examine technology-based mathematical tasks designed by the PMTs in detail. In line with the aim of the study, the Dynamic Geometry Task Analysis framework developed by Trocki and Hollebrands (2018) was chosen as the conceptual framework of the study. This framework consists of two components: (1) Mathematical Depth; (2) Technological Action. The component of mathematical depth focusing on the mathematical purpose served by a technology-based task is developed mainly based on Smith and Stein's (1998) Cognitive Demand Level framework and also some other related studies in the literature (Baccaglini-Frank & Mariotti, 2010;Christou, Mousoulides, Pittalis, & Pitta-Pantazi, 2004;Laborde, 2001;Sinclair, 2003;Stylianides, 2008;Zbiek, Heid, Blume, & Dick, 2007). The component of technological action points out technological affordances to reach the targeted depth in the task and is developed again through the use of some studies in the related literature (Arzarello, Olivero, Paola, & Robutti, 2002;Baccaglini-Frank & Mariotti, 2010;Christou et al., 2004;Hollebrands, 2007;Hölzl, 2001;Sinclair, 2003). While mathematical depth explains the purpose of the task in levels including N/A and 0-5, type of technological action consists of technological affordances described between N/A and A-F to reach the targeted mathematical depth (see Table 1). In the framework, two main parts are taken into consideration in the tasks: (1) the section seen on the screen drawn by dynamic geometry; (2) guiding questions called "prompt" related to the teaching objective. In this study, by employing this framework, we examined how the PMTs changed or developed their designed technology-based mathematical tasks in terms of mathematical depth and technological action through micro-teaching and classroom teaching.  (Trocki & Hollebrands, 2018, p. 123)

Allowance for Mathematical Depth
Levels Hierarchical Levels and Descriptions N/A Prompt requires a technology task with no focus on mathematics. 0 Prompt refers to a sketch that does not have mathematical fidelity. 1 Prompt requires student to recall a math fact, rule, formula, or definition. 2 Prompt requires student to report information from the sketch. The student is not expected to provide an explanation. 3 Prompt requires student to consider the mathematical concepts, processes, or relationships in the current sketch. 4 Prompt requires student to explain the mathematical concepts, processes, or relationships in the current sketch. 5 Prompt requires student to go beyond the current construction and generalize mathematical concepts, processes, or relationships.

Types of Technological Action
Affordances Descriptions N/A Prompt requires no drawing, construction, measurement, or manipulation of current sketch.

A
Prompt requires drawing within current sketch. B Prompt requires measurement within current sketch. C Prompt requires construction within current sketch. D Prompt requires dragging or use of other dynamic aspects of the sketch. E Prompt requires a manipulation of the sketch that allows for recognition of emergent invariant relationship(s) or pattern(s) among or within geometrical object(s).

F
Prompt requires manipulation of the sketch that may surprise one exploring the relationships represented or cause one to refine thinking based on themes within the surprise (adapted from Sinclair (2003, p. 312).

The Research Design
This study formed as a qualitative research was designed using an action research method, which is used to understand and solve an educational problem in a particular context (Charles & Mertler, 2002). In action research, researchers are aware of the expected impact of the intervention and possible changes that might occur through the research. Therefore, most action research focuses on consciously changing or developing a particular issue, in which researchers have key roles (Berg, 2004). In particular, the development of research is based on researchers" ability to organize, implement, improve and evaluate the newly introduced plan or process (Hui & Grossman, 2008). Action research is a cyclical process consisting of planning what to change, acting upon and observing the results of such change, then reconstructing the process through revision and reflection (Kemmis & McTaggart, 2005).
This study is part of a research project where we as the researchers (the authors of this study) examined the development of four PMTs" designing and implementing technology-based lesson plans in the context of a 14week Practicum course (Bozkurt & Yigit Koyunkaya, 2020). We designed an action research in three cycles (see Figure 1). The first cycle of the study was conducted between the 1st and 7th weeks to improve the PMTs" knowledge to design technology-based mathematical tasks and to plan the implementation processes of those tasks. The second cycle was about micro-teaching carried out between the 8th and 9th weeks to allow the PMTs practicing their tasks before classroom teaching. The last cycle focused on the PMTs" classroom teaching in their school placements and completed between the 9th and 14th weeks. In this process, due to the nature of the action research, during the transition from one cycle to the next cycle, we followed and examined the planning processes of technology-based tasks, micro-teaching and classroom practices. Accordingly, we designed individual action plans for each PMT during the research process (for example; conducting additional individual interviews, or repeating the micro-teaching process). In this study, we mainly focused on the second and third cycles of the research.

Participants
Participants of the study were four prospective secondary mathematics teachers, who were enrolled in the last semester of their final year of a mathematics education program at a Turkish University. Participants took almost all mathematics and mathematics education courses in their teacher education program, as well as technologybased courses such as Using Mathematics Software and Using Information Technologies in Mathematics Education. In addition, before taking the Practicum course, they took a course called School Experience in which they had an opportunity to observe classroom environments in school placements for a semester. While selecting the participants, the criterion sampling method, a purposeful sampling strategy, was used to provide detailed information about situations in depth (Merriam & Tisdell, 2016). Participants" knowledge and ability to use GeoGebra was considered as a criterion for their participation in the study.

Data Collection
Data in this study consisted of the PMTs" technology-based tasks, video recordings of micro-teaching and classroom implementations, and also interviews. The PMTs designed in general four or five technology-based tasks in their lesson plans. In this study, we focused on one task of each PMT that was selected and examined in detail. We as the researchers involved together in the selection process of the tasks by discussing the content of each task. In particular, within the conceptual framework, we paid particular attention to select and share some tasks in which the three PMTs showed some development and also a task in which one PMT could not propose much change or development. In terms of the chosen topics, the first prospective mathematics teacher (PMT1) designed a task to teach trigonometric ratios, the second one (PMT2) designed a task to teach the area of a circle, the third one (PMT3) designed a task to teach the area of a triangle, and the fourth prospective mathematics teacher (PMT4) designed a task to teach the base area of a shape formed by rotating a rectangle at different angles.
During the second cycle, the PMTs practiced their micro-teaching. After micro-teaching, each PMT was given feedback and suggestions by the researchers and fellow PMTs in micro-teaching. In addition, we conducted individual interviews with each PMT on this process and gave feedback to help them improve their plans and teaching. Then in the third cycle of the research, the PMTs revised their tasks based on their microteaching experiences and given feedback, then implemented their revised tasks in classrooms. All those processes were video-recorded as the main data of the study.

Data Analysis
For the data analysis, we analyzed each selected task by comparing and contrasting the aimed mathematical depth (MD) and planned technological action (TA) in the PMTs" plans, and also reached MD and used TA in their micro-teaching and classroom implementations in school placements. We investigated the changes and development that occurred among these processes. The tasks in the plans were analyzed with the document analysis method based on the conceptual framework of the study (Bowen, 2006). Also, video recordings collected in micro-teaching and classroom teaching were analyzed using video analysis method, in particular whole to part approach (Erickson, 2006). In this process, we followed the steps stated below respectively:  We watched all the videos as a whole without stopping and took notes,  We watched the videos again with stopping and divided into pieces according to the components of the framework. Then we transcribed the selected pieces and identified the critical events related to the framework.  By comparing the aimed and reached MD and TA in each process of the task (including the design stage, micro-teaching and classroom teaching), we analyzed how and why it changed or developed.
As a first step, we analyzed the PMTs" prompts in their plans to determine the levels of mathematical depth that they aimed to reach and the types of technological action they planned to use. Then, we identified changes or development in the PMTs" tasks by analyzing the videos of micro-teaching and classroom teaching. We particularly examined the prompts they asked during teaching, answers to those prompts, how they used the dynamic technology (such as use of dragging) and compliance with their plan at these stages. For instance, concerning the PMT3"s task on finding the area of a triangle, we identified, first, his intended mathematical depth, which was to guide students to reach the area formula of a triangle by using the area formulas of polygons (MD-1) and also his planned technological action which was to use the activity only as a visual (TA-N/A). Then, we watched the videos of his two micro-teaching (he conducted two micro-teaching) and classroom teaching of this critical event without stopping, and then the videos were stopped and watched again. At this stage, we transcribed the pieces related to his reached mathematical depth and used technological actions. All processes were compared and the changes or development were determined. Additionally, we transcribed and used the interviews with the PMTs and post-lesson discussions regarding the identified critical events that were used to support the data. In this sense, triangulation was used in order to increase the trustworthiness of the study (Patton, 2002).

Results
In this section, we report our analysis on each prospective mathematics teacher's targeted level of mathematical depth (MD) and planned technological action (TA) in their tasks, the level of mathematical depth achieved and the type of technological action used during micro-teaching and as well as during classroom teaching of those tasks in school placements. In particular, we compared their achieved MD and used TA in micro-teaching and in classroom teaching to identify the changes in the content of tasks and in teaching practices of the PMTs.

What PMT1 planned
PMT1 designed a technology-based task in which students could use right triangles and related elements to support the conceptual learning of the meaning of trigonometric ratios (see Figure 2). She planned to discuss how to find the length of the tree in the sketch using the sides of a right triangle and the ratios of these sides, and in this process, she expected students to gather information from the sketch (MD-2). Then, she aimed to explain the meaning of the trigonometric ratio of tangent in a right triangle, and planned to ask the following prompt, "If we only knew the value of tanN, could we find the length of the tree?". Then, she aimed for students to notice and explain how the trigonometric ratios were related to side lengths of the right triangle (MD-3 and 4).
At the last stage of her plan, PMT1 planned to discuss the following prompts on the possibilities that this tree could fall on the house:  If we could change the distance of the tree from the house, could we make different comments?  Let's fall down the tree by using the slider. What could you say about this situation?  Would it be enough just to change the length of the tree or the distance of the tree from the house?
In this process, PMT1 aimed for students to reach a generalization (MD-5) on how trigonometric ratios would change based on the changes in an angle through using dynamic features of the technology (TA-D) and guiding them to recognize existing relationships in the sketch (TA-E). Although she planned to ask some prompts with the use of a slider attaching to the tree in the sketch, she could not manage to design such a slider in the content of the task. She stated that she would work on this before implementing her task in microteaching.

Micro-teaching
In her micro-teaching, PMT1 only used the rules related to trigonometric ratios (MD-1) and enabled students to gather information from the sketch (MD-2). In terms of the type of technological action, it became apparent that she generally used her sketch in a static way (TA-N/A), but towards the end she partially used the dynamic features of the software by changing the height of the tree (TA-D). Detailing the whole micro-teaching process, she started her teaching by discussing the question in Figure 2 and expected students to make inferences in line with what they saw on the screen (MD-1 and 2). However, at this stage, PMT1 asked some prompts, which were not in her plan, that resulted in a different teaching direction from her plan. For instance, she asked "Have you ever heard of a concept called slope?" and guided students to find the length of the tree by discussing the slope concept. She then introduced the ratio of tangent as planned by pointing out the ratio between the side lengths. However, she did not ask the following planned prompt directly "If we only knew the value of tanN, could we find the length of the tree?". Instead, she discussed the content of this prompt by proposing different prompts than she planned, but with the prompts she asked, students only managed to collect information from the sketch (MD-2).
Later, PMT1 focused on the changes in trigonometric ratios while changing the height of the tree. For this purpose, she asked "What changes would happen if I move the tree?". As mentioned above, although she planned to attach the image of the tree to a slider to show the possible different situations of the tree falling down that could be analyzed by students (TA-D), she could not manage to add such a slider to the task. Instead, she only discussed the situation where the height of the tree was changed by dragging the corner point of the image of the tree (see Figure 3). In this process, she tried to support students" examination of the situation by only changing the height of the tree one time. Therefore, she could not manage to discuss how changes in an angle would affect the trigonometric ratios of this angle since she could not use the dynamic features of the software effectively. In this sense, PMT1 could not guide her students to construct conceptual knowledge regarding relationships between angles and side lengths (MD-3 and 4) or to reach a generalization (MD-5). In the interview after micro-teaching, she stated that she could not put her plan into practice during micro-teaching since she lost track of the details and directions of what she planned. Based on her experience and feedback during micro-teaching, PMT1 revised her task before classroom implementation. While revising her task, it became apparent that she still could not manage to add a slider attaching to the tree image. Instead, she drew a number of colored line segments to show the different heights and positions of the tree. Following her plan, she started her classroom practice by discussing how the tree's falling down situation was related to the side lengths of the right triangle. In this process, she guided students to make inferences through using their prior knowledge and collecting information from the sketch (MD-1 and 2). She then showed the tangent ratio of an angle. At this stage, as she planned, she effectively discussed the idea of finding the length of the tree by knowing the tangent ratio of an angle and guided students to make explanations considering the relationships between angles and side lengths (MD-3 and 4). Also, she helped them develop conceptual knowledge about other trigonometric ratios and the relationships between them (MD-3 and 4). However, she did not use any technological action until this stage; she only used the task in a static way. At the last stage of the task, although PMT1 wanted to take advantage of the dynamic features of the software, she had some problems in practice. For instance, to change the height of the tree and its distance from the house, she moved the position of the vertex of the right triangle (point K), but in the static picture she added to the task, the position and height of the tree did not change (see Figure 4).

Figure 4.
A redrawn sketch of PMT1"s dragging the vertex point K of the triangle PMT1 asked "For example, if I move point K, my tree is not moving right now, please ignore it. It is a static picture. What changes as I move point K now?". Since the location and appearance of the tree did not change, unclear answers came from the students. At this point, she tried to use the colored line segments, however, forgot the roles and functions of the line segments and became confused. In this sense, PMT1 experienced a number of difficulties in using the tools of the software (e.g. she did not measure the side lengths dynamically and forgot to close the dynamic texts representing these measurements). Nevertheless, she continued her teaching by dragging the line segment AO (orange colored) showing the height of the tree, and managed to guide her students to reach a generalization to some extent about how trigonometric ratios changed depending on the changes in angles and side lengths (MD-5) (see Figure 5). However, contrary to what she had planned in this process, PMT1 partially used the dragging feature (TA-D). Also, she was partially successful in using the task in a way for students to recognize relationships between trigonometric ratios and angles in the sketch (TA-E). Considering all the processes she experienced, it became apparent that PMT1 developed not only the content of her task but also the way she used it in her teaching. As it can be seen in Table 2, although she planned to guide students to reach a generalization regarding how trigonometric ratios changed depending on changes in angles and sides, in micro-teaching she did not achieve the targeted mathematical depth as she could not utilize her planned technological actions in an effective way. However, by considering her experiences and suggestions in the micro-teaching, she managed to achieve her planned aims to some extent in her classroom practice. She could not use the dynamic features of GeoGebra effectively. She asked the following question "What change would happen if I move the tree?" However, as she could not add a slider to the task, she only dragged the corner point of the image of the tree one time and enabled students to collect information from the sketch (MD-1 and 2, TA-N/A) She managed to guide the students to reach her aimed generalization. (MD-5; TA-D and E).

What PMT2 planned
PMT2 designed three different technology-based tasks to conceptually verify the area of a circle in his lesson plan. He aimed to verify the area by using an infinite-sided regular polygon in the first task, using sectors in the second task, and forming the circle into a triangle in the third task. In this section, we reported the results of his second task, namely verifying the area of a circle through using sectors.
In his plan, it became apparent that he did not indicate the targeted mathematical depth or planned technological actions for the implementation of the task, instead he only stated the aim of guiding students to reach the area of the circle. In line with this aim, he planned to use two different sliders (TA-D) while one of them attached to the radius of the circle, the second one represented the number of sectors in the circle (see Figure 6). Using this task, PMT2 aimed to guide students to reach a generalization about the fact that the area of a circle could be obtained from the area of a rectangle, which was evolved through the shape formed by combining the sectors as the number of sectors increased (MD-5) (see Figure 7b).

Micro-teaching
PMT2 experienced two micro-teaching. In the first micro-teaching, he practiced only his first task, which was about verifying the area of a circle by using infinite-sided regular polygon. During the process, he encountered situations that he did not plan to which he could not propose any solution. Hence, he ended the micro-teaching at his own request to conduct another micro-teaching later. Then, in his second micro-teaching, he implemented all three tasks he planned to teach. Considering the problems and difficulties experienced in the first micro-teaching, PMT2 was more successful in reaching his goal in the second micro-teaching. In micro-teaching, PMT2 started his second task by introducing the functions of the sliders and the content of the task. To indicate the area of evolving shape formed by interlacing of different colored sectors (see Figure 7a), he used the slider representing the number of sectors (TA-D) and asked students to observe how the area changed as the number of sectors gradually increased (see Figure 7b and 7c). In this process, he encouraged the students to discuss the following prompts:  I move this slider and increase the number of sectors. What happens to this shape (the shape formed by arranging the sectors)?  I constructed 44 blue sectors, 44 red sectors and rearranged them together in a shape. I am moving the slider; what do you think is happening to the shape?  What did the final version of the shape resemble?
Although he pointed out that the total shape resembled a rectangle through using hand gestures, a student asked, "Can we do it again from the beginning?". At this stage, it became apparent that students had difficulties in constructing and explaining the relationship between shapes and only managed to collect information from the sketch (MD-2). In response to the student"s request to repeat the process again, PMT2 animated the slider and prompted students on the animation (TA-D). In this way, he managed to better help students establish and explain mathematical relations about the evolving shapes (MD-3 and 4; TA-D and E). As a result, students reached a generalization on the relationship between the area of the rectangle and the area of the circle (MD-5). In terms of technological action, PMT2 managed to use the sliders effectively (TA-D) to reach the intended mathematical depth. Although he was more successful in his second micro-teaching, he experienced some difficulties in guiding students to reach his aimed mathematical depth. For instance, it was observed that he had a difficulty in answering the following question asked by a student: "why is the length of the line segment formed by the sectors 2 (pi)?". In the group discussion conducted after micro-teaching, fellow PMTs made suggestions regarding answering such a question. They also suggested that to better indicate that the shape formed by sectors resembled a rectangle as the slider increased, he should have emphasized the parallelogram image beforehand.

Classroom teaching
Considering his experiences and feedback given in micro-teaching, PMT2 revised his task before his classroom implementation. He started his practice by explaining the functions of the two sliders in the task: This slider represents the radius of the circle. Radius is a dependent variable here, so the radius changes when I move the slider. I also divided the circle into equal sectors starting with the minimum number 4 increasing to 6,8,10 till 60. So, the second slider represents the number of the sectors.
PMT2 initially expected students to collect information about the changes that occur on the sketch (MD-2) by animating the slider representing the sectors (TA-D). Then, he guided students to discover the relationship between variants (number of sectors and evolving shape) by asking how the sketch changes (MD-3, TA-E). In this process, he helped students realize that the shape formed by the sectors evolved from parallelogram to rectangle by using the concept of limit (see Figure 8). Then, PMT2 asked prompts about the area of the circle and expected them to provide explanations through relating the circle to the rectangle (MD-3 and 4). While students said that the short side of the rectangle was equal to the radius of the circle, they could not understand how the long side of the rectangle was formed. For example, a student asked a question regarding the long side of the rectangle: "When you move the slider into 60, should not the line segment indicating the long side of the rectangle stay constant? Why is it getting longer? Circumference of the circle is fixed, we only increase the number of the sectors". PMT2 answered the question by constructing a relationship between the length of the arc and the length of the line segments. He showed that the length of the arc had gradually evolved to the length of the long side of the rectangle by increasing the number of sectors with the slider. In particular, he changed the number 60, which was the highest value in the slider, into 1000 and enabled students to observe and notice the idea of approaching (see Figure 9). In this sense, it became apparent that PMT2 were able to respond to an unexpected question by using the technology in an effective way. After he guided the students to conclude the relationship between the long side of the rectangle and the circle, they reached a generalization of the area of the circle (MD-5).

Figure 9.
A redrawn sketch of PMT2 changing the highest number of the sector slider as 1000 In summary, considering his experiences and suggestions in his two micro-teaching sessions, PMT2 managed to use the dynamic technology effectively in his classroom implementation and was more successful in reaching the mathematical depth he aimed (see Table 3). He did not include specific prompts in his plan. He aimed to start his task by asking the following question: "How can I find the area of a circle?" He aimed to guide students to reach a generalization about the fact that the area of a circle could be obtained from the area of a rectangle, which was evolved through the shape formed by combining the sectors as the number of sectors increased (MD-5; TA-D).
In the process, using the slider representing the number of sectors (TA-D), he enabled students to collect information from the sketch (MD-2). Then, he continued dragging the slider (TA-D), but he had difficulties in reaching his aimed mathematical depth.
He enabled the students to collect information from the sketch by animating the slider representing the number of sectors (MD-2), to construct and explain a relationship between the number of sectors and the shape formed by the sectors (MD-3 and 4) (TA-D and E).

What PMT3 planned
PMT3 designed a lesson plan to teach how to find the area of a triangle. In the first task of his plan (see Figure 10), he aimed to reach the area of a triangle using the areas of polygons such as rectangle or square. At this point, he planned to use his task only as a visual (TA-N/A) and aimed to use the areas of rectangle and square (MD-1). In order to achieve this goal, he planned to ask students to calculate the areas of 4 different shapes in Figure 10 respectively. Also, for the triangle shape in the task, he aimed to ask students to turn this triangle into a square (using two equal triangles) and then to calculate the areas of those triangles and the square. At this part, if unexpected answers arose, he planned to teach the area of the triangle step by step by directing students to the first two shapes in the task. After students recognized that the area of the triangle was half of square and/or rectangle, PMT3 expected them to reach the area of triangle through calculating the area of the final shape (an irregular polygon) in the task.

Micro-teaching
PMT3 performed two micro-teaching. In his first micro-teaching, he followed his plan, and used the task as a visual (TA-N/A) and enabled students to reach the area of the triangle with the use of the areas of rectangle and/or square (MD-1). At this point, the researchers and the other PMTs who participated in the micro-teaching made suggestions regarding the fact that he could have used technology more effectively in line with his aim. For instance, instead of using the task as a visual, he could have explored the area of the triangle by drawing this sketch step by step in GeoGebra.
Considering these suggestions, PMT3 requested to practice another micro-teaching for this task. In his second micro-teaching, PMT3 drew an irregular polygon step by step (TA-A) and asked students how to calculate the area of this polygon (see Figure 11). When students replied that this polygon could be divided into a rectangle and two triangles, PMT3 asked about the area of the rectangle (MD-1) and guided them to create rectangles from those two triangles. He started a discussion for students to make and explain a relationship between these shapes (MD-3 and 4). Then, PMT3 continued on the ordinary board and enabled students to reach the area formula of the triangle based on the area of the rectangle. At the end of this micro-teaching, the participants suggested that he could verify the area of the triangle by dragging one side of the polygon that was constructed at the beginning. Figure 11. A redrawn sketch of PMT3"s drawing an irregular polygon

Classroom teaching
During the classroom practice, it was observed that PMT3 improved his teaching by taking into account his experiences and suggestions given in micro-teaching. Similar to his second micro-teaching, PMT3 drew an irregular polygon in GeoGebra (see Figure 12) and asked students how to find the area of this polygon as planned. While doing this drawing, he constructed a polygon with a right angle instead of a random polygon (TA-C) because he wanted to make use of the rectangle. This was one of the suggestions given in his second micro-teaching.

Figure 12.
A redrawn sketch of PMT3"s construction of an irregular polygon with a right angle PMT3 effectively used the software to verify students' answers while guiding a class discussion on how to find the area of the polygon. In this process, with the use of the GeoGebra tools (perpendicular line, parallel line), he constructed two triangles and a rectangle inside this polygon (TA-C) and measured the areas of each of these polygons (TA-B) (see Figure 13). During the discussion, he asked students to remember areas of the rectangle and triangle (MD-1) and to make predictions about the relationships between the areas of the shapes and explain this (MD-3 and 4). By turning the triangles into a square or a rectangle, he enabled students to verify/falsify their predictions. At this point, PMT3 dragged the irregular polygon (TA-D) and helped students realize that the equality of proportions between the areas did not change even though the polygon changed (MD-5) (see Figure 14). As summarized in Table 4, there were significant changes and development in the content and implementation of PMT3"s task. To guide the students on reaching the formula of the triangle from the shape by aiming to make use of the area of the rectangle and planned to use the task as a static image (MD-1, TA-N/A).
He achieved the goal by applying the task as he intended. After micro-teaching, researchers and other prospective teachers suggested that he could improve the level of mathematical depth of the task and use technology in a more effective way (MD-1 and 2, TA-N/A).
He drew an irregular polygon in GeoGebra and asked the following question "How could we find the area of this polygon?" (MD-2, TA-A).
His classroom implementation of this task was similar to his second micro-teaching.
What ratio do you think is there between the area of the triangle and the area of a quadrilateral created from two of this triangle?
He aimed to guide students to notice that area of a triangle is the half of the area of formed quadrilateral (MD-1 and 2, TA-N/A) As he planned, he asked the students about the ratio between the area of the triangle and the quadrilateral. Students made comments about the shapes using the area formula (MD-1 and 2, TA-N/A).
He drew an irregular polygon and discussed the relationship between the areas of the triangles and quadrilateral (MD-3 and 4; TA-A).
He constructed a polygon with a right angle (TA-C), and enabled the students to relate between the areas of the triangle and rectangle inside this polygon (MD-3 and 4), then by dragging a point of this polygon (TA-D) he guided the students to reach a generalization (MD-5).

Prospective mathematics teacher 4
4.4.1. What PMT4 planned PMT4 designed a task to teach the base area and volume of a shape formed by rotating a rectangle at different angles (see Figure 15). PMT4, in her task, used 3 different sliders representing the rotation angle, short side of the rectangle (the radius of the cylinder) and long side of the rectangle (the height of the cylinder). In this study, we share the results of part of her task related to the base area. She aimed to reach a generalization on how to find base area by rotating a rectangle at an angle (e.g., 360 o , 180 o and 120 o ) . In this process, PMT4 aimed for students to remember the base area formula of a cylinder (MD-1), to collect information from the sketch by observing the changes in the angle (MD-2), to explain the relationships that occur based on the changes in the sketch (MD-3 and 4) and finally to generalize the occurred relationship (MD-5). She planned to use the sliders at different stages in the sketch (TA-D) and aimed to achieve her goal by emphasizing the changes in the situations that occurred. For instance, she planned to ask the following prompt: "What could be the relationship between the base areas of a rectangle rotated by 360 o and then by 120 o ?". Then, by measuring the base areas of the geometric shapes (TA-B), she planned to discuss whether the students' predictions about the relationships were correct. As a result, she aimed to emphasize the relationship between the base area and radius by asking whether a change in radius would affect this relationship.

Micro-teaching
In the micro-teaching, PMT4 started the lesson by reminding the following information to the class "the cylinder is formed by rotating the rectangle 360 o ". She asked students about the relationship between the base areas of the shapes formed by rotating the rectangle 360 o and 180 o . She chose a student from the class to use GeoGebra in the front, whom she asked to move the angle slider first to 360 o and then to 180 o (TA-B and D).
At this point, by using the measurement tool, she confirmed that the base area of the shape formed by rotating 180 o was half the area of the cylinder. She then performed similar operations for the shape that formed by rotating the rectangle 120 o . However, she could not reach her intended mathematical depth since she could not effectively utilize her planned technological actions. For instance, she used the slider attaching to an angle to rotate the rectangle (TA-D) but did not guide students to make observations on the formed shapes in order to discover relationships and make mathematical explanations. Instead, she talked about the ratios using only the formulas related to the relationships of the shapes (MD-1). Then she asked the students whether the ratio between the base areas of the shapes changed when the radius changed. She asked the student (who was using the technology) to move the radius slider (TA-D), however she explained to the class that the ratio did not change by using the formula on the normal board (MD-1). In the last stage, she asked the following prompts: "What can I say about the base area of the rectangle rotated with a certain angle? Can I reach a formula dependent on the angle?". When students gave an answer as /360 o , she asked "Why?", but she made her explanation to the class without prompting further and was not able to guide students to reach a generalization about the fact.
At this point, it has been observed that PMT4 made use of the software by only using the measurement tool and the slider in a limited way. In particular, she did not make an effective use of her planned technological actions (using the slider) in the discussions and in the cases of verifying/falsifying the students' responses. In the group discussion held after micro-teaching, the other PMTs and researchers made critical comments about her teaching including the fact that PMT4 was prone to replying to her own prompts without allowing enough time for students to respond, and that her prompts were not clear in guiding the students to reach a generalization. Also, one of the comments was about her not using dynamic technology effectively in the discussion she aimed to create.

Classroom teaching
Despite the experiences and suggestions made in the micro-teaching, no significant difference was observed in PMT4"s classroom teaching. PMT4 started the task by asking students the relationship between the base area formed by rotating the rectangle at 360 o and the base area formed by rotating it at 180 o . After receiving the students" responses, she chose an assistant student from the class, who would be in charge of the technology in the front, and asked the student to measure the base areas of the shapes using the measurement tool in GeoGebra (TA-B) and verified the predictions of the students in the class (see Figure 16).
Likewise, she asked them to predict the relationship for the shape formed by rotating a rectangle at 120 o and tested students" predictions with the use of the measurement tool. In this sense, as stated in her plan, she asked her assistant student to change the angles (TA-D) for the class to collect information from the sketch about the shapes rotated by different angles (MD-2). She then asked whether a change in the radius would affect the ratio between the base areas of the shapes rotated by different angles, however, she did not make any manipulation on the sketch with the use of the radius slider to verify or falsify students" predictions. In this process, as she stated in her plan, she asked the class about their reasons regarding the predictions they made, but although students gave several answers, she ignored those and gave her explanations instead. At the last stage aiming for the students to reach a generalization, PMT4 asked about the formula of the base area of the shapes formed by rotating a rectangle by  degrees. After a couple of students responded to her question, she wrote the formula directly on the normal board without using her technology-based task. In this sense, she generally answered the prompts herself, directed the lesson on the normal board and could not guide the students to reach the intended mathematical depth, in which she used the measurement tool (TA-B) and sliders (TA-D) in a limited way. However, during the post-lesson interview, PMT4 stated that she felt that her awareness about her teaching increased and improved. She expressed that the reason why she could not reach the intended mathematical depth was related to the low participation rate of students in the classroom, which hindered her to create a class discussion. To conclude, PMT4 had problems in reaching her intended mathematical depth and in using the planned technological actions effectively during both her micro-teaching and her classroom teaching (see Table 5). This seem to be because she did not to take into account her experiences or suggestions given in the micro-teaching. How do we find the base area of a shape formed by rotating a rectangle at a specific angle?
By presenting situations regarding different angles, she aimed to guide students to establish and explain relationships and between the base areas of the formed shapes (MD-3 and 4; TA-B and D).
She changed the slider to the angles of 120 o , 180 o and 360 o and measured the base areas of the shapes formed. However, she could not guide students to compare the base areas at specific angles and construct the intended relationship (TA-B and D (limited)). (MD-1 and 2).
She did a teaching similar to what she did in micro-teaching and did not achieve her goal.
Would changing the radius change this relationship? Move the slider to change the radius. Is your prediction correct? Explain it.
She aimed to guide students to reach a generalization about the relationship between the base areas formed by changing the slider representing the radius (MD-5; TA-D).
She used the slider in a limited way and only guided students to use formulas and collect information about a couple of shapes formed (MD-1 and 2, TA-D).
She could not reflect her micro-teaching experiences to her classroom teaching. She mostly used the task as a visual amplifier and explained the intended relationship verbally.
In summary, Table 6 provides an overview regarding the processes experienced by the four PMTs. It became evident that although PMT1, PMT2 and PMT3 did not reach their goals during their micro-teaching, they managed to fulfil their targeted mathematical depth to some extent by using their planned technological actions in their classroom teaching. However, in PMT4"s case, there was not a significant improvement from her microteaching to her classroom teaching. Table 6. An overview of changes in the PMTs" tasks in terms of mathematical depth and technological action

Conclusions and Discussion
This study focused on the development of four PMTs" technology-based tasks through teaching practices. In particular, as suggested by Trocki and Hollebrands (2018), this study examined how PMTs targeted mathematical depth and planned technological actions of their tasks changed or developed during classroom practices. In micro-teaching, it was observed that PMTs could not reach the mathematical depth they aimed in their tasks or use their planned technological actions effectively (e.g., not being able to use the dynamic features of the software, aimless or limited dragging or not using the measuring tool). Additionally, during microteaching, there were a number of their inappropriate uses of mathematics vocabulary and notation. Furthermore, they could not use their prompts in the ways they planned. All of which had an impact on their failure to reach the targeted mathematical depth. After micro-teaching, it has been observed that there were positive changes and development in PMTs" classroom practices, during which they considered their micro-teaching experiences and also the suggestions given during interviews. In particular, PMT1, PMT2 and PMT3 developed their teaching of technology-based tasks considering the suggestions in their micro-teaching and interviews. However, in PMT4"s case, there was not much difference between her micro-teaching and classroom teaching in terms of the level of mathematical depth achieved and the type of technological action used, which indicated that she seemed not to consider and evaluate her micro-teaching experiences and suggestions.
The results of the study indicate that the PMTs in general improve the ways of teaching the intended mathematical knowledge (use of mathematical notations and conducting a class discussion) and also the ways they utilized the dynamic technology. In addition, all the PMTs stated that they changed the content or goals of their tasks after micro-teaching. In this sense, through micro-teaching, PMTs had the chance to determine whether they were able to reach their targeted mathematical depth in the tasks or use their planned technological actions and accordingly to develop the situations they were missing. In particular, PMT3 showed a notable change in the way he implemented his technology-based task. While initially aiming to use his task only in a static way (MD-1, TA-N/A), he made use of the measuring and dragging tools (TA-B and D) for students to reach a generalization on the area of triangle in his classroom teaching (MD-5) based on his micro-teaching experiences and suggestions. In other words, the PMT3 did an effective teaching by using the dynamic technology to help students explore mathematical relationships (Bowers and Stephens, 2011). In this sense, micro-teaching in this study provided an ethical and safe environment for the PMTs to experiment new tasks that did not risk the learning of students (Allen & Eve, 1968). In the interviews, all the PMTs indicated that microteaching was the most important part in this process and mentioned that micro-teaching contributed the most to the process of developing their technology-based tasks and teaching their tasks. This result, similar to the results of Akyuz (2016), highlights the importance of teaching experiences in PMTs" technology integration. Hence, the results of this study contribute to the field on how technology-based teaching of PMTs could be developed through micro-teaching.
The results of the study also point that the PMTs" individual and group interviews with the researchers, their participation in each other"s micro-teaching and classroom teaching, and also post discussions about each other"s teaching were the elements that affected the PMTs" development from micro-teaching to classroom teaching (Akyuz, 2016;Donnelly & Fitzmaurice, 2011;Griffiths, 2016;Zbiek, 2005). Also, the actions and questions of both the participants in micro-teaching and students in classroom teaching led to the PMTs revising and developing their technology-based tasks. In this sense, this study indicates that incorporating micro-teaching into Practicum courses is of crucial importance for PMTs" technology integration, in particular, considering the implied discrepancies between what teachers plan and what they experience in classrooms (Lagrange & Ozdemir-Erdogan, 2009;Ruthven, 2009). In this way, PMTs could be prepared for technology use in classroom teaching and such discrepancies could be minimized.
This study also shows the usefulness of Trocki & Hollebrands"s (2018) framework in two ways. Firstly, the PMTs realized that they could plan tasks with different levels of mathematical depth through the use of prompts. They also noticed that they should have considered and planned technological actions for the purpose of reaching their intended mathematical depth. Secondly, the framework has provided us as the researchers to examine and evaluate the content of the PMTs designed tasks. In detail, it helped us reach a general impression about the coordination of mathematical depth with technological actions, purpose and level of the task, especially in the process of coding each prompt in the tasks. In this light, this study provided the usefulness of the Trocki and Hollebrands"s (2018) model integrated into a Practicum course, which offered the PMTs a guidance in designing and developing technology-based mathematical tasks. This is of particular importance since Trocki and Hollebrands (2018) highlighted that there has been a limited number of studies on the design and evaluation of dynamic technology-based tasks (Trocki, 2015;Yigit Koyunkaya & Bozkurt, 2019) and suggested that future research should be designed especially on the effects of the use of this framework on prospective (practicing) teachers" professional development. Hence, similar to our study, future studies could make use of the existing technology-specific frameworks in teacher education programs to improve PMTs" knowledge, experience and skills in technology integration in order to contribute to the related literature.