After making their own observations students will begin to ask questions. Have a brainstorm session. Just in case you have difficulties developing some research questions, here are some examples to get you started. Have each individual or group choose a question they would like to pursue and note it in their journal. Allow students to make predictions based on their previous observations.
Pill bugs prefer apples to lettuce.
Ask students to develop ways to test their questions. Creating a data collection table may help students organize the information as they gather it. Keeping variables constant is a challenge for scientists. Students usually understand the concept of being fair. The analogy of a group of people playing the same game by different rules often illustrates the importance to students.