Whats with the $ coin?

I bought this app for my 6 year old. Its engaging and she enjoys it, but it is confusing her since the sizes of the coins need to be more true to life...they are too similar. Also, the $ coin looks too much like a penny for early learners. Should probably ease them in with progressive learning and eliminate the $1 coin since no one in the states uses a $1 coin anymore.

ScrabbleStar! about Amazing Coin (USD) Dollar