The children were learning about light. Here is a video they have been looking that helped them understand how it travels.
Gravity, Force, and Work (clip)
GRAVITY, FORCE and WORK introduces Zog to Newton's basic laws of motion. By observing objects on earth and in space, Zog learns that nothing can start moving, speed up, slow down, change direction or stop unless a FORCE is applied to it -- even if the force is hard to see, like GRAVITY or FRICTION.
What is gravity?
Bobby & Adam, as part of their school's project to celebrate National Science and Engineering week make a BrainPOP type movie telling us all about Gravity.