My daughter started watching MSB when she was 3-4 years old, and it held her interest until she was 10. The episodes are fun and engaging while being educational at the same time, so children learn without even knowing it! Don't let the school age children in the series deter parents of younger children... Pre-K and Kindergarteners will delight in the show too.
Synopsis of this episode (from the back cover):
Topic: Food Chains
Arnold and Keesha are in trouble when they forget an assignment to bring in two things that go together. He has a soggy shoe with pond scum he stepped in on his way to school. Keesha has only the tuna fish sandwich she brought for lunch. Ms Frizzle is delighted at the brilliant combination! A field trip to the ocean becomes a search for the connection between these two unlikely objects. The bus shrinks and travles through the ocean food chain - getting eaten along the way!