Planning Your Investigation These general procedures should be used when conducting your lab: Use a very small piece of a saltine cracker for each sample tested. Break up the saltine into small pieces to simulate chewing. Do not actually chew the cracker sample to be tested. Spit into the containers with the samples that are being exposed to amylase. To keep the volume consistent between samples with and without amylase, you may dilute your saliva with water. Use a tablespoon to measure liquid volumes. Add the iodine only when you are ready to test the results. Do not eat any of the samples after they have been exposed to iodine. Before you start your experiment, consider these questions: What is your independent variable? What is your dependent variable? What are your control variables