Addition Strip Board
The addition strip board is a numbered board with blue and red strips that a child of about 5 lays end to end to find and memorize the sums to 9 + 9. On October 5, 2026 it cost $27.00 to $76.20 at the US sellers we checked. A card version takes about an hour to make.
The first lesson with it is Addition Strip Board. Not sure your child is ready for it? Two minutes of questions place your child on the sequence.
| Area | Math |
|---|---|
| Used in | |
| From age | 5 to 7.5 years |
| Make it | Easy to make at home |
| Buy it | About $27 to $76 (noted ) |
What the addition strip board is for
The child lays a blue strip for the first number at the left edge and a red strip for the second right after it, then reads the sum printed above the end. Working through one table at a time, the child writes every fact and checks it against a chart.
The board isn't in Montessori's books of 1912 to 1917, which add with the red and blue number rods laid end to end. It comes from the later albums.
| Part | What it looks like |
|---|---|
| Board | 12 squares down by 18 across, numbered 1 to 18 along the top |
| Blue strips | Nine, 1 to 9 long, solid, numbered at the end |
| Red strips | Nine, 1 to 9 long, divided into squares, numbered |
| Charts | Not included in the boards we checked; the build below makes a simple one |
The lessons that use the addition strip board
Addition Strip Board
5 to 7.5 yearsLaying a blue strip and a red strip end to end on a board numbered 1 to 18 and reading the sum above, to learn the addition facts to 9 + 9 by heart.
Buying one: 3 listings checked October 5, 2026
| Seller and set | Made of | Price |
|---|---|---|
| Alison's MontessoriAddition Strip Board (M14)Sale price; regular $30.00. Nine red and nine blue strips. No charts. | Plastic board, wooden strips | $27.00 |
| Montessori OutletAddition Strip Board (510500270)Sale price; market price shown $76.20. Board 12 by 18 squares, nine red and nine blue strips. No charts. In stock. | Wood | $29.95 |
| NienhuisAddition Strip Board (009200)Nine red strips divided into squares and nine solid blue strips, numbered 1 to 9. No charts. | HDF, birch plywood, beech | $76.20 |
- Alison's and Montessori Outlet's boards cost under $30 and have the same strips as Nienhuis's at $76.20. Alison's board is plastic; the others are wood.
- Check that each strip is an exact number of squares long. A strip even slightly long gives wrong sums.
- None of the three includes the addition charts. Make a control chart by writing out the tables.
- Montessori Services and The Montessori Room had no addition strip board when we looked.
Making the addition strip board at home
What to gather
- A sheet of stiff white card at least 40 by 28 cm
- Blue card and red card
- A ruler, a fine marker and a craft knife
| Piece | Size and marking | How many |
|---|---|---|
| Board | 18 by 12 squares of 2 cm, numbered 1 to 18 along the top | 1 |
| Blue strips | 2 cm wide, 2 to 18 cm long | 9 |
| Red strips | 2 cm wide, 2 to 18 cm long, ruled into 2 cm squares | 9 |
- 1Rule the board into 2 cm squares, 18 across and 12 down, leaving a top strip for the numbers.
- 2Write 1 to 18 above the columns.
- 3Cut the strips, write each strip's number at its right end, and rule the red ones into squares.
- 4Check every strip against the board's squares before use.
- 5Write the 1 to 9 tables on a sheet as the control chart.
Keeping a full set on the shelf
- Keep the blue strips and the red strips in two separate stairs in their box.
- Replace any card strip that bends; a curled strip reads wrong.
Questions parents ask about the addition strip board
What is the strip board in Montessori math?
A board numbered 1 to 18 with strips 1 to 9 long. The child lays two strips end to end and reads the sum. There's also a subtraction strip board.
Does the addition strip board come with charts?
Not the three we checked. Addition charts are sold separately or written out at home.
Can I make an addition strip board?
Yes. Card ruled in 2 cm squares and colored card strips work well if every strip is cut to an exact length.
Before the addition strip board, make sure the work before it is solid. The stamp game lesson lists the signs that a child is ready to move on.