TL;DR Wunderkeys Piano for Preschoolers Book 1 is the most effective way I have found to begin preschoolers at the piano.
WunderKeys Preschool 1 is a fantastic resource for teaching piano to children ages 3 to 5. Its story-based format with engaging characters and off-bench activities makes learning fun and exciting for young students. This program builds foundational skills like pre-reading, keyboard awareness, and rhythmic understanding, setting the stage for future musical success. The inclusion of teacher-student duets requires teachers to have intermediate piano skills. Overall, WunderKeys Preschool 1 is a comprehensive and delightful way to introduce preschoolers to the piano. Highly recommended for piano teachers.