The Big Dog Problem - Peg's yard. When Peg and Cat need to mail some important letters for Peg's Mom, they find their path to the mailbox blocked by a really big dog. Primary Content: Height; Secondary Content: Direction, sets that can't be divided equally.The Three Friends Problem - Peg's yard. When Peg and Cat are playing with their new friend the Big Dog, Cat suddenly becomes strangely quiet. Using a graph, Peg attempts to figure out what's wrong with Cat. Primary Content: Bar graphs; Secondary Content: More, less.