Thursday, January 25, 2001
Sci Tech Observation
The agenda for the day was written in the upper right hand corner of the board: Quizlet, Ramp Lab Review, Mousetrap Lecture, Mouse Trap Lab. There were examples of previous mousetrap cars along the right wall of the room and examples from student journals and lab write ups in the back. There were also motivational statements along the top of the walls. There were 13 males and 8 females in the class and the students segregated themselves by gender. There are three teachers in this class: 1 certified teacher, 1 long-term substitute and 1 student teacher.
Students started the class with a 10-minute quiz over previous material. After the quiz, one teacher walked them through what was expected of them in a lab write up. She indicated that the previous lab reports were less than acceptable. On the board were bulleted notes about the lab report contents. These notes were not particularly organized -- they jumped from one section to another without being in chronological order. This may be due to space constraints on the board. It seemed that longer items were paired with short items to fill up space. Each lab report must have a purpose, background information, materials, procedure, data, sample calculations and a discussion. The teacher emphasized detail in the procedure section. She stated, "If you don't write it down, it never happened," and gave students examples from their last lab of how to make their procedures more detailed. The last lab was an efficiency lab where students calculated the potential energy of a ball at the top of a ramp at a given height. They then calculated the kinetic energy and rotational of the ball at the bottom of the ramp and divided the bottom energy by the potential energy to find efficiency. In terms of making the procedure more detailed, she told students to include how high the ramp was, the mass and size of the ball, whether the ball was dropped or placed on the ramp, the distance the ball was allowed to travel at the bottom, and so on. She stated that students must provide a T-error on all measurement devices listed in the materials section. Data calculations must have the appropriate scientific notation. On the last lab, the calculations should have gone to the second decimal place and no farther. Scientific notation for efficiency is fixed at 2 places. Students must include sample calculations in their data section. The following example was on the board.
Pe=mgh
Potential energy = mass of ball X acceleration due to gravity X height.
45.5(g) X 980 (cm/s2) X 20.5 (cm) = 14 e+5 ergs
Students were pretty attentive during the lecture on lab format. After this lecture, another teacher began the mousetrap lecture. The mouse trap lecture was more interactive than the first lecture. The second teacher asked more questions of the students and got the class more involved. In this lab students used a mousetrap with a string attached to the arm of the mousetrap and spring scale attached to the string. A one-cm square of paper was taped to the mousetrap end of the string and there was a protractor taped to the long side of the mousetrap.
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The teacher showed the students how to use a model set up and then passed it around for students to look at. Students were to measure the angle of the mousetrap arm and the force exerted on the spring scale. They had to be sure that the spring scale was always perpendicular to the mousetrap arm. The 1 cm square of paper was to help students make sure that the spring scale was always perpendicular to the mousetrap arm. The teacher also told students they had to calculate distance. He asked the students how they would do this and one student quickly provided a formula. The other students had no idea how he got it so the teacher went over the math behind the formula (d= q/360 X 2pr). He also showed the students how they should set up their data table: one column for force, one column for angle (q), and one column for distance. He asked the students if the thought the force would be constant or vary with distance. Students thought the force would vary and they predicted the graph of force vs. distance would have a line with a positive slope. The teacher told the students they would plot their data onto a graph and find the best fit line. He wrote the equation of the line on the board (F(d) = md + b). When the teacher asked how the students would find the equation, they were confused. Evidently in their lab the day before, students were given the equation of the line and asked to calculate the area under the line. The teacher pointed out that this time they would have to find the equation of the line first before they could calculate the area under the line. He then led them through using their data to figure out m and b in the formula. The third teacher then led the students in a series of questions about the theory behind the lab. She used note cards as she called on the students. Her first questions dealt with why the string had to be perpendicular to the mousetrap. It took several students to come up with the answer that the distance needed to be perpendicular so distance and force would move in the same direction to determine work.
The students then broke into their lab groups and gathered their materials. The three teachers went around the room and made sure students were using the lab apparatus correctly. They encouraged the students to be careful in their data collection because "the lab results are spectacular when the lab is done correctly." During the lab, I had the opportunity to ask one of the teachers about some things I noticed. I asked her why their was such an imbalance of gender among the students. She said there were equal numbers of males and females in the Science Academy but that the difference in this class was due to scheduling. She also described how and why she used the cards in the class discussion. She said she had picked up the technique from another teacher. She has one card per student. At the beginning of class she shuffles the cards so students can't predict if they will be called on. She then calls on the student listed on the top card and records whether their response was right or wrong. She said this was a great tool for several reasons. She used to use questions as a way of picking on students who weren't paying attention. This method ensures that she will pick on random students and they pay attention because they know she may pick on them and because they know she records whether their answer is correct. It also serves as a way to show administrators and parents that she gets participation from all students and it serves as an assessment tool. At the end of each 6 weeks, she gives students a participation grade that is based on the number of correct answers on the cards. During lab, students were very busy in their groups collecting data. They worked in groups of 3 or 4 (mostly 3) and no one was off task. As students got neared the end of their data collection, the teachers decided to have them hand sketch a graph of their data. This would help students determine whether they had accurately measured all their data points. After they hand sketched the data they would go to the computer lab and graph the data with excel. Students were just finishing up their data collection when the fire alarm went off. I had to return to UT before the end of the fire drill so I was unable to observe the rest of the lesson.