The more test subjects improves the validity of the results. The length of an experiment is included in the procedure and is usually 2-4 weeks. After an experiment is completed, some students will repeat or continue the experiment for more information. Some students will setup two or three experiments to run at the same time. Students also need to obtain as much data as possible.
Data is any information that the student can observe, measure, and then record.
It is used to determine if the hypothesis is valid or invalid.