Lesson Plan – Triangles

Mental and Oral StarterUsing mini white boards pupils to draw rectangles with the given areas.

Main ActivityUsing mini white boards and slides 4-7 ascertain pupils prior knowledge and recap the methods used to calculate the area of a triangle. Remind pupils that they need to know the height and base of the triangle and not the length of the sloping sides. Give out the ‘today’s task’ instruction sheet to each group and briefly talk through the instructions with the class. Make sure that pupils understand their roles. Discuss the learning outcomes and explain that the group should only include rectangles in their design if there is someone in the group who needs further practice at working out the area of rectangles.

PlenaryPupils to reflect on the success criteria for the Habits of Mind and Maths Objectives

Objectives and Habits of Mind

Level 4 - To accurately measure the length and width of rectangles to the nearest mm.Level 5– To find the area of a rectangle using formula.Level 6 – To find the area of triangle using formula.•I can work well in a group, listening attentively and taking on different roles when needed.•I can negotiate and follow ground rules, to ensure fairness and cooperation when working with others. •I can identify the best information to help complete a task and put it into my own words.

Keywords: Area, Base, Height, Formula

LO To find the area of triangles. RAG

Key Words: Base, Height 21 Apr 2023

Starter Activity

Mini white boards ready !!!

Show me………

Area = 12cm2 Area =

40cm2

Area = 15cm2

How would we find the area of the rectangle?

7cm

4cm

So area of the triangle must be -

How would we find the area of the rectangle?

7cm

4cm

So area of the triangle must be - 4 x 7 = 14cm2

2

So we can deduce that…

the area of any triangle must be -

Base x perpendicular height

2Even if……..

Perpendicular height

base

base

So you’re looking at a triangle and you want to find its area.

What do you do?

1. – Think – where would it’s rectangle go?2. – Think – where do I need to measure to find the area of it’s rectangle?

3. – Find the area of its rectangle by multiplying base x height.

4. – Halve your answer.

10cm

6cm

10 x 6 = 60

60 ÷ 2 = 30 cm2

Level 3 4 5 6 7 8ShapeSpaceMeasure

I understand and can explain the difference between area and perimeter.

I can find the area and perimeter of shapes by counting squares.

I can find the area of rectangles and squares using a formula.

I can find the area of triangles, kites, parallelogram trapeziums and circles. I can use formulae for the volume of cuboids. I can find the volume and surface area of cuboids.

I can calculate volumes and surface area of prisms and cylinders.

I understand the difference between formulae for area, perimeter and volume by considering dimensions.

Today we are learning

I am starting the lesson on level _____________________

By the end of this lesson I want to be able to _____________________

Key WordsPolygon Length Width

Height Perimeter Area

Surface Area Volume Circumference

Radius Diameter Pi

Today’s Task

•Work out the area of each individual triangle and / or rectangles showing your working out. You will need to measure them to the nearest mm.

•Fit them together to make a design.

•Find the area of the design.

Use these triangles.

1. Cut them out.

2. Find their area.

3. Fit them together to make a design.4. Find the area of your design.

Use these rectangles if someone in your group needs to practice using the formula for the area of a rectangle.

1. Cut them out.2. Find their area.

3. Fit them together to make a design.4. Find the area of your design.

Habits of Mind Success Criteria

•I worked well in a group, listening attentively and taking on different roles when needed.

•I negotiated and followed ground rules, to ensure fairness and cooperation when working with others.

Score yourselves from 1-5 with 5 being the highest score.What could you have done differently to get a higher score?