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Sensorial Decanomial


Building a square.
Discrimination of size, shape, and color.

Preparation for mathematics: squaring.

Control of Error
Visual disharmony

4 years


A large mat
A large square board
A box with:
- 10 squares increasing in size from 1cm x 1cm to 10cm to 10cm, in plastic (or cardboard).
- Each square has corresponding rectangles, except for the square 1cm x 1cm.
- Each square and its corresponding rectangles are of a different color.


Invite a child and have him unroll a large mat. Bring him to the shelf and show him the box we will be using. Tell the child that today we will be working with the Sensorial Decanomial. Have him bring the box to the mat and have him place the box in the upper left hand corner. Have the child sit near the left side of the mat and you sit to the child’s right.

- Remove all of the squares from the box.
- Grade them centered on top of each other from largest to smallest on the left side of the mat.
- Show the child where to find the large board and place it on the right half of the mat.
- Place the red square in the upper left corner of the board.
- Place the green square on the diagonal of the red.
- Return to the box and take out the two green rectangles.
- Place them around the green square to complete the full square.
- Place the pink square on the diagonal of the green square.
- Remove the four pink pieces from the box and place them to complete the square.
- Place every square on the diagonal of the one before it and fill in with the pieces from the box (with the help of the child), until the whole of all the pieces creates one large square.
- Then show the child how to place all of the squares and rectangles back into the box: placing the square of each back into its correct slot and then placing the rectangles of the same color one on top of each other from largest to smallest.


Exercise 1
The child works individually as in the way shown during the presentation.

Exercise 2
Have the child build using all of the squares and rectangles as shown in the presentation. Remove one band of color (usually the 6th or 7th row: the purple or white rows). Place them onto the mat and move the other rectangles or squares up, and removing any unneeded rectangles onto the mat.

Exercise 3
Have the child build as in the first presentation. Then remove one of the bands, as is Exercise 2. Using the unneeded rectangles and square, build as may squares as possible.

Exercise 4
Have the child build as in the first presentation. Take out one of the larger squares (either coming from the 9th or 10th row). Place it on the mat. Take out a smaller square and place it in the top left corner of the large square. Explore by taking out other squares or rectangles needed to complete or fill in the square. Once that is done, slide off this “newly made square” and try creating another large square made up of smaller squares and triangles.

No language is given with this material.

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