Identify variables that will need to be controlled. Students should agree on what makes a good experiment. Each lab group could work on a different variable if you wish. Discuss how many trials are necessary before you have enough evidence to make a statement about rotifer feeding rates. Ask students to come to agreement on how the class will conduct their experiments before you begin.
Students can all do the same thing or each lab group can vary the procedure they develop.
Be aware that the microscope light will heat up the animals and may influence the feeding. Consider the amount of daylight exposure as well. Elaboration Allow students to work on their experiments. Offer suggestions and ask them questions. Provide the stained yeast as a food source to start with.