Montessori AMI Primary Guide
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Numbers through Ten
  Number Rods
  Sandpaper Numbers
  Number Rods and Cards
  Spindle Boxes
  Concept of Zero
  Cards and Counters
  Memory Game
Decimal System
  Introduction to quantity
  Formation of Numbers
  Stamp Game
  Dot Game
  Word Problems
Linear & Skip Counting
  Teens: Quanity
  Teens: Symbol
  Tens: Association
  Linear Counting
  Skip Counting
  Number Roll
Tables of Arithmetic
  Addition Snake Game
  Strip Board - exercises
  Addition Strip Board
  Addition Charts
  Substraction Snake Game
  Substraction Strip Board
  Substraction Charts
  Multiplication Bead
  Multiplication Board
  Multiplication Charts
  Unit Division Board
  Division Charts
Passage to Abstraction
  Small Bead Frame
  Wooden Hierarchical Material
  Large Bead Frame
  Racks and Tubes

Substraction Snake Game


- A quantity of varying bead bars of the board stair, usually 5 of
each (kept in a special box or bowl reserved for the snake game.
- A black and white bead stair.
- A quantity of ten bead bars (in a box)
- An assortment of grey bead bars (subtraction bars)
- A special notched card for the purpose of counting and marking.
- Two boxes or trays; one to contain the addition bars and the other to contain the subtraction bars that have been counted.


  1. Have the child bring the material over to the table.
  2. Have him unroll the mat.
  3. Have the child open the boxes of beads and place them above the mat.
  4. Remind the child of each of the beads in each box.
  5. Have the child set up the black and white beads in stair formation.
  6. Show the child the last bead box.
  7. Take a few out, have the child count them, and point out that they are the same as the black and white bead bars but they are gray and dark gray. Emphasize that these are the subtraction beads.
  8. Tell the child that we will make a bead snake as we have been doing.
  9. Tell the child what colored bead bars to place in the snake. It is good to have this first example come out to zero. See below for an example:
  10. Colored Bead Bars             Grey Bead Bars
           7 ------------------------------------ 4
           2 ------------------------------------ 5
           5 ------------------------------------ 9
           8 ------------------------------------ 7
           6 ------------------------------------ 8
           4 ------------------------------------ 6
           9 ------------------------------------ 9
           1 ------------------------------------ 6

  11. Alternate randomly from colored bead bars to gray bead bars.
  12. Start counting the colored bead bars with the card counter. When you get to 10, exchange it for a ten bar and count how many beads are left. Place that number with the corresponding black and white bead bar.
  13. Place the original colored bead bars into the empty box.
  14. Repeat in this way until you reach a grey bar.
  15. When you do, bring it to the child’s attention.
  16. Turn the grey bar back and count it. (For example: 4)

  17. montessori, tables of arithmetic, substraction snake game illustration   montessori, tables of arithmetic, substraction snake game illustration

  18. Say, “That means we need to take away four.”
  19. Take four away from what you have already counted. Place the grey colored bars into the empty box, but return any golden bars to the golden supply
  20. If there are more beads on the bar that you have just “taken away”, count the beads that are left and place that number in the black and white bead bars. Place the black and white bar into the snake and place the grey and colored bead bar(s) into the empty box.
  21. Repeat in this way until you have subtracted all of the grey bars in the snake.


To familiarize the child with the subtraction facts.

Control of Error

  1. Let’s have a look at all of the bars.”
  2. Have the child place all of the gray bars in a vertical stair formation from longest to shortest.
  3. Have the child place the colored bead bars in the same manner below the grey bars.
  4. Pair the grey bars and colored bars by placing the longest of each together. Place these pairs vertically at the bottom of the mat.
  5. Exchange if needed to have the same amount of colored bead bars as grey bead bars.
  6. Do this until there are no more grey bead bars to match.
  7. Then match the golden ten-bars with the rest of the colored bead bars. (They should be a perfect match.)

5 1/2 - 6 years

Personal Note
This work should not be done until the child fully understands the Addition Snake Game.

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