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?