Speaking as an educator...
This is a very useful show. I have used episodes of this in several lower age group lessons and the kids love it. And why not? The episodes even follow the Three Stage lesson plan, a short introduction demonstration (the starter) a repeated and slowly developed set of central themes and ideas (the main session) followed by a recap (those awesome songs, the plenary).
I have even used the odd episode with older kids, up to about 16 years old (the episode on the earth's structure as it happens)! Oh sure they are a bit hesitant to admit it, but they loved the episode and learned a lot.
This is some of the most useful TV I have come across.