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.
We opened class with a brainstorming session about what would happen if a person placed a Saltine cracker in their mouth and left it there. Students in each class came up with two or three hypothesis statements, after which, they conducted the experiment. Students were offered regular or whole wheat crackers. We recorded observations, determined whether the observations supported or disproved the hypothesis statements, and then launched into a discussion of enzymes. Students recorded the definitions of reactants, products, and enzymes taken from today’s Chemistry class Lesson 35 PowerPoint slide deck (on slide 11, the word “catalyst” was replaced with “enzyme” and “substance” was replaced with “protein”). We reviewed the way that animals and plants created polymers of glucose to create glycogen (energy stored in animals), starch (energy stored in the plant organelle called the amyloplast), and cellulose (structural molecule in plants). We then applied that learning to the discussion of how the salivary amylase enzyme digests the starch in the Saltine crackers, releasing glucose molecules. A few students in each class who let the crackers sit in their mouths for a long time even reported the crackers tasted slightly sweet. The discussion of enzymes set the stage for tomorrow’s potato catalase lab.
Pictures from the white boards for today’s classes: