The first thing I learned in this unit was physical change. Physical change is when something is changed but is still the same thing that you started with. Next, I learned about chemical change. When this happens you see bubbles and a gas forming. I also learned about matter. All of the things around us is matter. One thing I liked is the experiment with the cabbage juice, soda and chloride. When we mixed it, it got fizzy and the bag got big. I really liked this unit, there really was nothing I didn't like. Why does bubbles and gas form in a chemical change?