Recommended Age: 4 years and onwards
Level of Parent Involvement: Medium during the initial presentation then low once the child has been shown and can work independently. The adult must also make the materials prior to the presentation.
Prerequisites
- The child should have worked with the first and second sets of constructive triangles and be able to name the shapes formed by the triangles
Materials
- Set 3(triangular box) print from PDF
- Scissors
- Laminator
- Laminating sheets
- Small tray or box to keep the constructive triangles
- A mat for the child to work on (you may use a towel if you don’t have a work mat OR small carpet mats are available from most carpet stores which are perfect work mats for children doing Montessori exercises from home)
Preparation
- Cut out triangles
- Laminate triangles then trim around the plastic laminating sheet
- Place the triangles in the tray/basket
Steps
- Invite the child letting them know that today you are going to show them the third constructive triangle exercise
- Let the child know they need their work mat, once the child has placed their mat they may bring the tray/basket of triangles to the mat
- Take out all pieces from the tray/basket and place on the mat, the child may help
- Invite the child to place the same coloured pieces on top of each other
- Point out the grey triangle saying to the child “I wonder if we can make this same triangle with our other triangles?”
- Take the 2 green right angled scalene triangles, positioning them so their black lines are facing
- Slide together making all black lines touch, forming an equilateral triangle
- Take the 3 yellow obtuse angled isosceles triangles, positioning them so their black lines are facing
- Slide together making all black lines touch forming an equilateral triangle
- Take the 4 small red equilateral triangles, positioning them so their black lines are facing
- Slide together making all black lines touch forming an equilateral triangle
- Say to the child “let’s check to see if we have made the same triangle” (referring to the large grey equilateral triangle)
- Place the grey equilateral triangle on top of the other triangles, showing the child they are the same size
- Mix all the shapes
- Invite the child to have a turn, leaving the child to work independently
- When the child is finished let them know to place the 3rd set next to the 2nd and tell the child they may now explore the 3 sets they have been shown together
Variations
- The child may now use this set of triangles with the first and second set
- You may give the child the language of the parts of the triangle:
Side, angle, base, vertex (relates to the grey triangle)
Altitude/height (relates to the black lines on the joined green triangles)
Centre, angle bisector (relates to the black lines on the joined yellow triangles)
Midpoint of the side (relates to the joined red triangles)
- The child may trace around the triangle cards and label the parts
