Do you know of any exothermic reactions that can be conducted in high school (a.k.a. not very volatile)?

I'm looking for exothermic reactions that can be conducted in a high school, in other words, with substances typical of high schools. I'm doing an experiment where we have to measure the rate of a substance's reaction to another substance. I know we definitely have hydrochloric acid, sulfuric acid, sodium hydroxide and some other acids. Please provide some options. Thank you.