How High is the Sky by Anna Milbourne

Pipkin the penguin wants to know how high the sky is.  He has a bird and a hot air balloon take him up, but can't find the end of the sky.  Fold-out poster illustrates how high various parts in the sky are, all the way up to the moon, but the sky is still bigger.

How Big is a Million by Anna Milbourne

Pipkin the penguin wants to know how much a million is.  So, he searches to find things that are big.  He finds, 1, 10, 100, 1000 and more, but he has trouble finding a million.  Finally, in a fold-out poster at the end, his mother shows him a million of something.  Great for illustrating how huge a million really is.