Your students will ask to stay in from recess for this. It is the most popular unit I've taught in 32 years, and it is packed with challenging critical thinking.We imagine students are training at the school for spies: mini survivor challenges, mini crossbows, a jewel heist, footprint mysteries, memory games, cipher disks, case files, messages hidden in gel caps. This unit is STEM and critical thinking at its coolest and finest, and we’ve thrown in reading, speaking and listening, and a social-