Since most preschoolers can name the fruit on sight, watermelon makes an iconic treat to teach preschoolers about the letter W. You can offer thin slices of the melon to the child on a paper plate, and teach them to cut the fruit to resemble the letter W with a plastic knife. If they don't have the dexterity for the task, you can offer them thin rectangular slices that they can assemble into the letter.
Slice Watermelon into building blocks similar to Duplo or Lego brand building blocks. Blocks allow the preschooler to explore their creativity and enjoy cleanup afterwards by eating their blocks. Direct their efforts to build simple things such as houses or cars and use the opportunity to discuss concepts such as inside, outside and various parts such as doors and windows. You can also freeze their art to view later or to enjoy as a healthy frozen treat.
The seeds from a watermelon make great additions to a preschool artistic endeavor. If you cut a paper plate into halves or quarters, the child can paint them like watermelon slices. Color the outer rim of the plate green like a rind, and the inner portions red like the watermelon's flesh. Use poster paints, washable markers or crayons. Glue real watermelon seeds onto the red portion of the paper watermelon for a tasty-looking work of art.
Make a creative musical activity with watermelon seeds and a paper plate. Clean and dry the seeds first. Have the child place the seeds onto a paper plate and then fold the plate down the middle, capturing the seeds inside. Glue or tape the plate shut. Your child now has a shaker to rival any maraca. For even more watermelon-based artistic flair, you can color the shaker with crayons, washable markers or paints to resemble a smiley-faced wedge of watermelon.