The procedure must explain how you will measure the amount of change. If you need special equipment, a local college or business may be able to loan it to you. Professional science supply houses are located in larger cities. They will have just about anything you will need. Do the experiment and record all numerical measurements made.
Data can be amounts of chemicals used, how long something is, the time something took, etc.
If you are not making any measurements, you probably are not doing an experimental science project. Keep careful notes of everything you do, and everything that happens. Observations are valuable when drawing conclusions, and useful for locating experimental errors . This could be in the form of a table of numerical data or graphs. It could also be a written statement of what occurred during the experiments.