In science class, harry and his classmates are performing a controlled scientific investigation. the teacher has already picked a topic and testable question for the class to study and has provided background research on the topic. before performing the investigation, the students must first

Before performing the investigation, the students must first form a hypothesis to predict the outcome of the investigation.
First they will need to try and make a prediction about what will happen in the investigation. They cannot yet analyze the data of the results or discuss the results themselves if they haven't yet performed the investigation. So obviously first they will try to guess what's going to happen.