Seriously. I don't know how he does it. Here is his method of teaching place value to a five-year-old (well, okay, I grant you, she'll be six next month, but still...).
Materials (graph paper glued to craft foam, total cost: about $5):
Then you plug in a number, choose the correct set of foam blocks to represent that number (so many hundred blocks, so many tens, so many ones) and then count by hundreds, tens and ones to figure out what the number is:
By day two we're adding two three-digit numbers by adding in each group (adding hundreds, adding tens, adding ones) and "trading up" for the next largest blocks size whenever we can. (Ten ones blocks can trade in for one ten block, etc. Here comes long addition and carrying!)
And in two days he has her correctly defining and understanding place value to the hundreds. All over the Labor Day weekend, while he's "on vacation". You know, "just for fun". Because they both love math. Can you hear the incredulity in my voice, people??