Is it possible to get a refund of more than was paid in?

Yes, the tax code is full of "refundable" credits, especially for low income parents.

These credits show up on the following forms & lines:

-Form 1040EZ, lines 8a & 11

-Form 1040A, lines 42a, 43, 44, & 45

-Form 1040, lines 66a, 67, 68, 69, 72 & 73