Fill the empty water bottle with colored water using food coloring.
Use different color masking tape or markers to mark water levels on the paper cups.
Make sure to mark the levels on the higher side. This will help achieve full forearm pronation.
Ask the child to take the filled bottle and fill the cups up until the water reaches the marker.
Encourage proper pronation of the wrist while filling the paper cups.
For grading, use a squirt bottle to work on finger strengthening as the child is squeezing the water out of the bottle to fill up the cups.