Saturday, December 1, 2012

Subitize & Make Five with the (free!) Number Rack

Having great fun with a kindergarten group. Yesterday we thought about what makes 5. We did a little subitizing and made use of the Math Learning Center's free app, Number Rack, that is also available as an online application for those who don't have a mobile device. Since I was a portable classroom (working in the hallway), I used my iPad. The kindergarteners were so impressed...until I said it wasn't mine! Here's one of the activities we did:

First, I showed them my virtual Number Rack and explained that today we'd only be using the red beads.

I asked them how many red beads I had.

Then I changed the configuration and asked again.

And again. "How many red beads?"

And again. "How many red beads?"

And again. "How many red beads?"

Eventually most of them started laughing. "There's always FIVE BEADS!!!"  After they straightened me out, I explained the next step.

First, I would hide some red beads on the right side of the screen under a flap. I'd set it up like this, but they wouldn't see any red beads at all, at least at first...

Because I'd make it even trickier. I would cover the beads on the left with my hand, move my hand to flash them a REALLY QUICK glimpse of what was hiding, and then cover it up again. They'd have to tell me what was hiding on the main (left) part of the screen based on their quick view (subitizing.)

After they guessed, I'd show them what was there. Then they could try to figure out how many red beads were hiding on the right side of the screen and we'd check by pulling down the ? flap to check.

I learned a lot about students' number sense. Especially "Dan's." At first, I thought Dan had the concept of making five. When 2 beads were seen, he said that 3 were hidden. But then when 3 were shown, he said that 4 were hidden. When 4 were shown, he insisted that 5 were hidden. Later I worked with him individually using a 5 frame. We have a bit more work to do!

Try out the Number Rack. Do a little subitizing. And "make five" math! (Or make five math friends!)


  1. Replies
    1. Thanks! Getting them ready for college math. ;)

  2. I love this....thanks, can't wait to use it with my K4 class

    1. You are so welcome! Let me know how it goes. :)


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