In the spring of 1937, ERPI scored a surprise "blockbuster" with Adventures of Bunny Rabbit. Its widespread appeal was partly due to narrator James Brill ending with a question directed towards the kindergarten and first grade students watching, one that was repeated by their teachers: "And now Bunny is once more with his mother. What do YOU think he is telling Mother Gray Rabbit – and what do YOU think Mother Rabbit is telling Bunny?" Animal pictures were among ERPI's (and later Britannica's) best sellers with popular late 30s and '40s titles as Three Little Kittens, Snapping Turtle and a post-war dramatization of Aesop's The Hare and the Tortoise (later redone in animation).
