If you've ever met Mr. Zaccarro you'd know why your kids love his material, what a fun, kind, and engaging man! My eldest DS when he was 10 (now 19) was able to have lunch with Mr. Zaccarro and my wife. Ed had my DS so excited about math I thought his head was going to pop off when I saw him afterwards, he couldn't stop talking about math and how it plays into everyday life.