Look What I Found! (Math)

I happened to be going through some school books, and came across this Math house that I used with Jack around 8 years ago.  It had a quarter inch of dust on it because it was sitting on the top of a big book shelf.  So I dusted it off for Eva and Joy.  They were quite excited to play with the felt numbers and sticks.  I really like it because the girls get a visual of the number houses that cannot have more than 9 in each house.  They seemed to catch on pretty quickly.  So, in this picture I asked Joy to "do" the number 46.

As you can see, Joy has the 4 bunches of 10 in the Ten House, and she is counting out 6 sticks for the Ones House.

Joy was successful, so we gave Eva a turn for the number 30.  See the problem?  She did not realize it until she actually put the sticks in the house and could see that they did not make 30.

Eva is very good at transposing numbers and letters.  If I ask her to pick out the number 76 on the chart, she'll usually pick out 67 instead.  Now that she realizes she makes this error regularly, I can see her mind working overtime when I ask her a question.  She's a little slower to answer, but I'd rather she get it right than get it fast.  She has come a long way from not even being able to combine a consonant with a short vowel just this time last year.