Does your school need a shelter? Whether your students are concerned about tornadoes, sharknadoes, or a zombie apocalypse, reinforced concrete is the answer! Learn about the history and chemistry of concrete. Make your own. Design a test to evaluate the strength of your concrete, based on anticipated threat (the natural or unnatural disaster of your choice). Conduct that test using small, preformed slabs. Making and breaking concrete is easy and fun, but wear your play-clothes. You will get dirty.