This is an investigation I created to complement the third grade FOSS science unit involving classroom crayfish. I wanted my students to understand the various steps of the scientific method and get hands-on experience with it. This investigation guides the students through the steps, asks them to define each step ("A hypothesis is _______."), and uses sentence frames to support all learners as they try to figure out the foods that crayfish eat. The Results section allows for 6 different foods to be tried, but I left that open-ended so other classes can choose their own! Enjoy!