Sensorial Lesson: Brown Quadrilaterial Prism

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“We have already pointed out that the function of the sensorial materials is
not to present the child with new impressions (of size, shape, colour, and so
forth) but to bring order and system into the myriad impressions he has
already received and is still receiving.”
—Dr. Maria Montessori

BROWN QUADRILATERIAL PRISM

Materials

10 brown wooden quadrilateral prisms, each 20 cm in length and which each
increase in width and height by 1 cm each. They range from the thinnest brown
stair being 1 cm wide by 1 cm high to the thickest prism, which is 10 cm wide and
10 cm high.

Presentation
1. Invite your child to work on the “brown stairs” by saying, “remember when we
did the pink tower from largest to smallest? Today we will grade the brown stairs
from thickest to thinnest.”

2. Have your child roll out a rug on the floor of your home.

3. Show your child where in your home the brown stairs are located.

4. Starting with the thickest brown stair, use both hands around the middle of the
prism to carry it to the rug.

5. Place the thickest brown stair at the bottom of the rug.

6. Continue using two hands to place the brown stairs in mixed order in a straight
line at the bottom of the rug.

7. Say to your child, “I will grade the brown stairs from thickest to thinnest.”

8. Choose the thickest brown stair and move it using two hands to the upper left side
of the rug.

9. Continue to grade the brown stairs horizontally from left to right or thickest to
thinnest.

10. When finished grading the brown stairs, use two hands to pick up the thinnest
brown stair and move it along the top edge of each brown stairs.

11. Show your child how to use your index fingers to move the thinnest brown stair
up each prism.

12. Run two fingers across the even surface.

13. When you complete the lesson, return the brown stair lesson to the appropriate
place in your home in the same manner it was taken down.

Note: I sometimes give my child a marble to have them roll down the brown stair after it
is built…super fun!

Vocabulary
thick, thicker, thickest, thin, thinner and thickest

Purpose: Direct
Order, concentration, coordination and independence

Purpose: Indirect
Preparation for a mathematical mind (decimal system)

Age: 2 ½ to 4 years old.