From PBS KIDS: Yet Another Tree Problem: The tables are turned! Peg is stuck up in the tree and Cat must figure out how to get her down… by making a ladder out of found objects. Primary Learning Goal: Up, down. Secondary Learning Goal: Horizontal, vertical. The Romeo and Juliet Problem: Peg and Cat help their poetic pal Romeo reach Juliet’s balcony using a series of horizontal and vertical lines. Primary Learning Goal: Horizontal, vertical. Secondary Learning Goal: Parallel.