Like Libby the pony, we all learn a lot from our parents as well as grandparents. Carrying through on that theme, have the students make a card for each of their grandparents and thank them for all the things they have done for them.
An alterative activity is to have the students make up a story about a pony.
Another activity (separate file) is to color the picture of the horse, adding trees, a farm, city buildings or whatever else desired.