What happens to the motion of a set of books when forces act on it?

Today we did an essential exploration where students were testing what happens to the motion of a set of books happens when forces act on it. They had 2 spring scales and a set of 6 leveled readers. They attached a spring scale to each end of the book. For the first 2 trials, they applied the same force. As I was walking around, we discussed what was going on with their exploration. I asked, "What happens when you both apply the same amount of force?" Most replied--the book didn't move because the forces are balanced. We learned yesterday that balanced forces are forces of equal strength that act on an object from opposite directions so that the object’s motion does not change. They remembered!!

But for the last 2 steps, one partner applied more force and they noticed that the books moved in the direction that the partner was applying more force. We discussed that unbalanced forces will cause a change in the motion of an object and can cause an object to move, start, and speed up or slow down. They are so smart!! They said they loved the experiments today too!!

RJ and his partner doing the exploration.

Hali and Natalie recording their data.