Below are some of my favorite STEM sites for teaching transdisciplinary STEM activities and getting ideas for what you want to do in your classroom. I am not paid or endorsed by any of these! If you have others you love, please let me know.
STEM Curricular Materials
Noyce Connections Conference at Kennedy Space Center Lessons (Created by NSF Noyce Fellows!)
Whitebox Learning System (Created by UK Graduates!)
Discovery Education – STEM Resources
PBS Learning Media – STEM Resources Collection
CSUnplugged – Computer Science without a Computer