Students began the day with an entry task asking them to reflect back on the potato catalase lab from before the break, locate and/or recall how temperature was affected by the reaction, and then to use science thinking to come up with a “why” statement. Students successfully reasoned through the idea that the increased temperature observed during the reaction was attributed to the net release of energy from the bonds breaking from hydrogen peroxide and reforming to produce water and oxygen. Students were then introduced to the vocabulary terms of exothermic and endothermic. After the entry task, we briefly reviewed the Unit 2 calendar, clearly noting the scheduled quizzes, project deliverables, and dissection week. Students were then treated to a job posting showing the clear market demand for individuals skilled at dissection. Students were then released to:
- Work with their lab group to complete and turn in the lab report
- When finished with the lab report, repeat the potato catalase experiment with fresh potato, baked potato, and frozen potato.
We wrapped up the calendar year with students working with their groups to write the conclusion section of the potato catalase lab report. The picture below provides guidance for writing the conclusion. When finished, students shared their lab report with the teacher and turned in their individually completed paper graphs.
We continued our work from yesterday, with students re-grouping to share the data from the lab (and creating T-charts of the data) and using it to create graphs using graph paper. Students then analyzed the graphs to answer questions about what the data demonstrated. The analysis questions were intended to help prepare students for the types of questions they might see on the Biology End Of Course Exam in May, as well as deeper questions that better reflect the thinking of highly capable high school students. For example, students were pushed to describe the enzyme’s rate of activity (the rate of change in their graph). Students have learned how to calculate the slope of a line in algebra, but it is not necessarily a concept students readily apply to biology. Students who finished continued working on their lab reports using the Chromebook, creating digital versions of their data tables and a few even created graphs in Google Sheets and copied them over to their Google Doc lab report. Students will finish the lab reports tomorrow.
We began the lesson with students reflecting back on the vocabulary words they learned on Monday (enzyme, reactant, and product). Students used the vocabulary to describe the chemical equation written on the board. The equation showed the enzyme catalase converting the reactant hydrogen peroxide (H2O2) into the products water (H2O) and oxygen (O2). Students then learned that catalase is an enzyme found in animals and potatoes. The enzyme has one of the fastest known reaction rates, converting 5 million H2O2 molecules into H2O and O2 every second! Students learned that we would be conducting an experiment with potatos to measure the rate of oxygen gas produced from the reaction of potato catalase with hydrogen peroxide. After writing down the procedure and watching a demonstration of the steps, students were assigned to groups and worked through the experiment, collecting initial and final temperature readings, as well as the change in oxygen percentage released over 10 minutes. Once the experiment was underway, students who were not actively timing or recording the results were assigned the job of typing up the procedure using the Chromebooks. We will analyze the results tomorrow.