My heart will go on: A guided inquiry Daphnia heart rate lab to teach experimental design

In this lab, which is used at the beginning of the General Biology sequence, students measure and manipulate the heart rate of Daphnia magna. In the process, students are introduced to working with live organisms, microscope use, and experimental design. The first part of the lab activity introduces students to microscope use and teaches them how to measure the heart rate of Daphnia. Class data are gathered and graphed to show natural variability and teach students how to use Excel to make basic graphs. Then, students design and carry out a simple experiment to alter the Daphnia heart rate with a physical or chemical treatment, again graphing their results. Students use their results to learn how to write a Materials and Methods and Results section of a scientific paper.