The reaction that this resource showcases is definitely a fan favorite. I have performed this many times in front of large audiences and it never ceases to amaze them. The link is going to take you to the experiment blog where Mark Rober shows how he made a super-giant elephant toothpaste reaction using chemicals that are hard to come by. If you scroll about half way down the page, there is a link to an activity that you can actually do at home. It requires simple ingredients that you can find at the grocery store and the quantities needed are so small that you can do this over and over again. The reaction is an exothermic reaction, so heat is going to be released, but it should be safe to touch with rubber dish washing gloves. The resource does a fantastic job at describing the science behind the reaction and uses appropriate terminology that is good for building scientific vocabulary. Further inquiry can continue with the suggestions at the bottom of the resource, which take some of the ingredients and turn them into variables.