Finding the Area of a Triangle Teaching Notes

Finding the Area of a Triangle Teaching Notes


KNOW: Students will know that the area of a triangle can be calculated using a formula.

Students will know that there is a relationship between the area of a triangle and the area of a rectangle.

DO: Students will find the area of a triangle using a formula.

Students will manipulate triangles in order to discover the relationship between triangles and rectangles.

Students will discover that any triangle is half of a rectangle.

Year and Level: Year 6 Level 4 Measurement


Activity 1: Finding the area of a triangle. **Each step represents a new layer

1.  Students are asked to measure the base and height of the triangle using a ruler and label the diagram with the measurements.

2.  They are given the formula to find the area and asked to insert their measurements and complete the calculation.

Activity 2: Placing the triangles into the rectangle. **As there is only 1 layer all steps apply to layer 1

1.  Copy the two orange triangles, changing the fill and outline colour to blue.

2. Move the orange triangles into the rectangle.

3.  Rotate the blue triangles and fit next to the orange triangles inside the rectangle.

** Rotate triangles before moving into the rectangle – It helps to move the Rotation Centre Position into the centre of the triangle

Activity 3: Find the area of the rectangle. **Each step represents a new layer.

1.  Students find the area of the rectangle and by inserting their measurements into the formula

2.  Discuss how two triangles fill the rectangle

3.  Discuss how the area of a triangle is half of the area of rectangle and connect back to previous question

Extension: Another way to work out the area of a triangle

1.  Students calculate the area of the triangle and the square

2.  Students move the triangles into the square

3.  Discuss how this can happen