Tinkercad is a starting place for 3D design. It walks students through the process step by step and is an excellent way to expose younger students to the design process.
Wisconsin 9/11 Memorial & Education Center
The Wisconsin 9/11 Memorial & Education Center’s website offers free lesson plans specific to teaching students in Wisconsin about the events of September 11th, 2001. While it is specific to Wisconsin, the lesson plans can be easily adapted for any location. The site also offers field trip activities and links