My son's teacher sent home a set of cards showing additive and multiplicative relationships between numbers.[br][br]I have been known to misplace things, or to leave them at home when I travel, so I made this digital version.[br][br]Instructions:[br]1. Click "New Problem".[br]2. Look at the card that shows up. Figure out what number best replaces the question mark.[br]3. Enter your response in the box labeled "Missing number =" and click "Check Answer".[br][br]Features:[br]You can click the operations in the center of the card to switch between two options: either Addition/Subtraction or Multiplication/Division.[br][br]The applet tracks which problems you get right and wrong. You can immediately retry a problem until you get it right, but only your first response is scored.[br][br]You can enter Review Mode to retry problems you missed. I recommend that you do a few other problems before you enter review mode. When you get a problem right in Review Mode, that problem is removed from the list of problems you missed. Changing operations will reset the list of solved problems.[br][br]Currently, the Hints checkbox expresses the card in English. In a future version, it may represent the card using a ten-frame or area model. It's clear how to do this when the unknown is up top (the sum or product), but I'm not really happy yet with my ideas for doing this when the unknown is on the bottom (an addend or factor).[br][br]I may experiment with the timing of review exercises, such as automatically bringing out the next review problem after three other problems have been seen--no review mode needed.

By the way...if you have a paper copy of these flash cards, you can just hold them by one corner (so your thumb blocks whichever fact you want to figure out). Say your answer and pull the card from the pack to check it. Rotate the card as you put it at the back of the pile, so it will give you a different challenge next time you see it. Go through the deck three times.