I’ve been recently teaching Physics to 8th graders. We have finished the chapters on motion, forces, and friction, and just covered gravity. As part of this chapter, though not included in the curriculum or book, I introduced the concept of the free body diagram . In the first session introducing this concept, most students didn’t really grab what it is or why it is important.
For the last session before the vacation, I started the class by playing a video of the Ariane 5  launch that occurred on 29 August 2013 of the French Guiana:
Note: if can’t see the video click here.