Physical changes only change the appearance of a substance, not its chemical composition. Chemical changes cause a substance tochange into an entirely substance with a new chemical formula. Chemical changes are also known as chemical reactions.
You can cause a physical change by bending, ripping, melting (and refreezing), folding, breaking, and there are some others. The main deal with physical changes is that the substance isn't formed into something new, that would be a chemical change.
