Looking for some simple, inexpensive STEM activities to use with your class? Want to create STEM Mystery Bags? Need a good icebreaker activity for the first days of school? Then you need STEM Challenge Cards. This download contains sixteen different STEM challenges perfect for individual students, pairs, or small groups. The challenges are flexible and open ended, and each one comes with a list of suggested materials. They are a great way to encourage critical thinking, problem solving, and creativity in your students.