Friday 4 September 2009

The addition snake game

This work has become a favourite at the moment. It is to help with addition and to show how a number of units can be exchanged to a 10 unit bar of the same value. The first couple of time Ebi-kun didn't totally 'get it' but now he can do the whole thing by himself and I have discovered he can count in 10's (well he sometimes forgets 30 but he is getting there). For those who haven't done this before I will walk through the steps...

First, take out the equipment, you will need a box with 10 of each 1 bead bar to 9 bead bar, a good amount of 10 bead bars, the black and white bead bars, a card divider and a piece of red felt (red is the Montessori colour for addition)
Lay the felt out and place the black & white beads in a pyramid, the white beads should be on the right.
Take out a random handful of bead bars, ask the child to guess how many are there, Ebi-kun likes to write down his guesstimate. Arrange the beads into a 'snake'.
Start counting from the left-hand side, in this picture some beads have already been exchanged for the gold beads. So the counting starts from the first black bead.
Count from the first (black) bead until you get to 10, put the card marker between bead 10 and 11.
Now, take a 10 gold bead bar, this will replace the 10 beads you have just counted.
Before you replace it though you need to count how many beads are left on the bar, it this case there are 3 yellow beads left (see above photo), the remainder beads need to be replaced with a black & white bead bar. In this example we replaced the coloured beads with a 10 gold bead bar and a black 3 bead bar.
Repeat the process until you reach the end of the snake, chances are, you will have a few beads left over.
The completed snake. You can then place the 10 bead bars together and count them in 10's, add the black beads and see if your guess at the start was anywhere near the correct answer. He guessed 43 but there were 83.

Once he had done this a few times I showed him that he could write it as an addition sum
He took one look and told me it was too difficult then I showed him how it matched the beads, he grinned and said 'easy'.
The next step will to be show him how to use the coloured replaced beads as a control of error but I will wait until he can do the above completely with no help first.

I must admit, I don't really know what the point of the white beads are in this exercise, if there is another Montessorian out there who knows the answer, please share!


  1. The white beads show after 5, so the child can see that 5+1=6, 5+2=7, and can find those beads quickly without having to count.

  2. I was also taught to make 2 short bead stairs one with the 1 at the top and the other with the 1 at the bottom. then you make the snake taking a bead from the top of each stair, so 1 and a 9, then a 2 and an 8, then a 3 and a 7 and so on. when you count you will find the pairs add up to 10 so you don't need the black and white stair. you put the 2 beads together as they are exchanged for a 10 bead bar and use these to illustrate bonds to 10.

  3. thanks Linda, I thought it might be something like that but I wasn't 100% sure.

  4. Annicles - I like that idea too, I might present that as a 'new' piece of work - variation on a theme. Thanks.

  5. the other way to do it is to make "snakes" on paper ( i laminate them as I have 30 preschoolers!) use any and all numbers and start with the sum in tens (10, 20, 30, 40, etc). so you might have a snake that's 5+4+3+6+1+2+8+1.... the child lays out the colored beads to match and then "exchanges" the colored beads when he gets to ten... the white beads are what we call "place holders". I find that a half of a bread closer thing works well... ore the starbucks thing you put in your hot drink to keep it from spilling! :)


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