Together we review all the signs to look for with physical and chemical changes. Then, I ask the students to predict what they think will occur when they pour this liquid on the Styrofoam cup. After discussing it together, I have the students pour it on to the cup. The reaction is somewhat fast, so they have to be ready!
This is not the only activity that we explore when talking about physical and chemical changes. We have also explored whether changes in states and mixtures and solutions are physical or chemical changes. You can also discuss physical and chemical weathering.