A while ago my sister introduced me to the book Mr. Base Ten Invents Mathematics. My boys loved it because it was a very concrete method of introducing the concepts of multiplication, division and subtraction that even younger kids could understand. The boys and I have been slowly learning the multiplication table. I made a Magic Math Machine to make doing flashcards a lot more fun.
Start with a box and cut some slits. Mine are about 3 inches by 1/2 inch.
Then I cut a piece of card stock....
...so that it fit in the box like this.
Then I creased the ends and taped them to the outside.
On the inside it should look like this, a "rainbow".
For a little extra support I added a card stock "wall" around my "rainbow".
I made some flashcards that were long, about the same length, but skinnier, as the card stock I used for the "rainbow". If the flashcard is the same width as the hole (like the one above) you'll have problems getting it to come out the bottom.
...and the card goes in the top...
...and the answer comes out the bottom!
Voila, the Magic Math Machine!!