Constructive Triangle - Rectangular Box B MONTESSORI Sensorial Lesson

Constructive Triangle - Rectangular Box B
Material:
A rectangular box
All the triangles are blue with no black lines
A pair of equilateral triangles
A pair of isosceles right-angled triangles
A pair of scalene right-angled triangles
A smaller scalene right-angled triangle
A scalene obtuse-angled triangle
A rug or large table
This material bought from:
Nienhuis Montessori USA | The Nienhuis Montessori materials
www.nienhuis.com
Presentation:
Invite a child
Introduce the activity
Have the child set up the floor mat
Have the child carry the box to the floor mat and sit-down
Open the box
Take all the triangles and place them around the box
Close the box and place it on the right corner of the floor mat
Start joining the triangles together according to the shapes: squares, rectangle, rhombus and trapezoid. You can always invite the child to form the shapes when you think he’s ready.
Isolate the square
Hold one triangle, move the triangle on the right with two fingers counter clockwise to the left to make parallelogram
Pause, slide one more time to the left, to make rhombus
Do the same one more time so it goes back to the square
Do the same with the rectangle, the rhombus and the trapezoid.
Invite the child to do this activity
When the child is done show him how to put the activity away:
Mix all the triangles
Open the box
First the square, 2nd: the rectangular, 3rd: the rhombus, 4th: the trapezoid. Keep the shapes
Note:
You may show only one shape and you leave the child to do with the other shapes
Following Exercise:
Sliding and Flipping.
Could be another day or depend on the child
Invite a child
Introduce the activity
Have the child set up the floor mat
Have the child carry the box to the floor mat and sit-down
Open the box
Take all the triangles and place them around the box
Close the box and place it on the right corner
Start joining the triangles according to the shapes: squares , rectangle, rhombus and trapezoid. You can always invite the child to form the shapes when he’s ready.
Isolate the square
Hold one triangle, move/slide the triangle on the right with two fingers counter clockwise to the left to make parallelogram
Once you make a new form then you flip the triangle and join them together
Do the same with all the shapes
Control of Error:
There is no control of error, because this one is exploration
Direct Purpose:
To show the constructive power of the triangles by exploring all possible shapes by using only two triangles
Indirect Purpose:
Indirect preparation for geometry
To show that all plane figures constructed with straight lines are composed of triangles
Preparation of understanding the concept of equivalent and its application for finding the area of plane figures
Age:
Between 4 - 5