Experiments with Daphnia & Scientific Posters
Over the course of about three days near the end of the summer, students investigated the effect of various substances (e.g. epinephrine, caffeine, alcohol) on the heart rate of Daphnia, as a way to understand how such substances can disrupt our own circadian rhythms.
We began by introducing the organism, Daphnia, first by giving students a mystifying description and asking them to draw what they thought it might look like. Then we gave a quick presentation before letting students practice observing the actual animals under the microscope and measuring their heart rate, following this handout as a guide. The flexible format of this activity allowed them to explore at their own pace, while we circulated around the room to help struggling students. Because students were working in pairs, they often were able to solve issues by themselves without needing teacher intervention.
After students had familiarized themselves with Daphnia and the procedure for measuring its heart rate, we then introduced the research project. Previously, we had guided students through the process of generating hypotheses and designing controlled experiments. Now we introduced the research cycle (see first picture above) and instructed each team to update their progress through the cycle as they performed their research.
After teams designed their experiments, they shared and gave feedback through an informal seminar. Teachers also participated in giving feedback and advice. The students then were given time to execute their experiments, analyze their results, and create posters presenting their research. To prepare them for the poster-making, we modeled a real scientific poster made by Mrs. Gill, who gave a mock presentation. We also guided students through the process of abstract-writing and data analysis using Excel. Poster-making took longer than we had anticipated, and so we postponed the poster session rather than forcing students to present an incomplete product.
Finally, teams took turns presenting their posters (some examples shown in pictures above) in front of the class, while observing students filled out a peer evaluation sheet (see example in last picture above). We designed this as a way for students to practice their listening skills while demonstrating their understanding of scientific research and poster principles.