In one of the games students could "buy" different objects on cards if they gave the correct amount in coins. We noticed that most feel comfortable using pennies, and no matter how large the amount, they would rather count out 47 pennies than try and use combinations of other coins. So you can help you child by letting them see different ways to add up to the same amount using different coins.
As far as putting numbers in expanded form (Where 473 is 4 hundreds, 7 tens, 3 ones, or 400+70+3), it's still a little hard for many to grasp fully. If you remember, driving home or eating dinner or whenever you have a minute with your child, play a game of breaking apart numbers (one says "31" the other "three tens and one one") or adding and taking away ten. It should help them become more familiar with the idea.
Today we did a lot with combining shapes to make new shapes, matching shapes to their outline, and breaking bigger shapes and objects into smaller shapes.
I know this may be repetitive, but if you haven't gone to our "link to language" classroom yet and listened to/recorded vocabulary, please take a look. I know it will really help:)
Your children are great! And brilliant.