National curriculum content

• Identify 3-D shapes, including cubes and other cuboids, from 2-D representations
• Know angles are measured in degrees: estimate and compare acute, obtuse and reflex angles
• Draw given angles, and measure them in degrees (°)
• Identify:

• Angles at a point and one whole turn (total 360°)
• Angles at a point on a straight line and ½ a turn (total 180°)
• other multiples of 90°

• Use the properties of rectangles to deduce related facts and find missing lengths and angles
• Distinguish between regular and irregular polygons based on reasoning about equal sides and angles

Lesson objectives

1. Understand and use degrees
2. Classify angles
3. Estimate angles
4. Measure angles up to 180
5. Draw lines and angles accurately
6. Calculate angles around a point
7. Calculate angles on a straight line
8. Lengths and angles in shapes
9. Regular and irregular polygons
10. 3-D shapes

What we want children to know

• To become increasingly accurate drawing lines to the nearest millimetre.
• To accurately measure angles with a protractor to the nearest degree.
• To recognise and use conventional markings for parallel lines and right angles.
• To use the term diagonal and draw conclusions about the angles formed between sides, diagonals and parallel sides, and other properties of quadrilaterals, for example using dynamic geometry ICT tools.
• To use knowledge to calculate missing angles and relate these to missing number problems.

What skills we want children to develop

Use knowledge to solve reasoning and problem solving questions such as:

Always, sometimes or never true?

• Two acute angles next to each other make an obtuse angle.

• Half an obtuse angle is an acute angle.

• 180˚ is an obtuse angle

Other possibilities

Here is one angle of an isosceles triangle. You will need to measure the angle accurately.

What could the other angles of the triangle be?

Are there any other possibilities?

Mathematical Talk

• Compare the angles to a right angle. Does it help you to start to order them?
• Does moving the paper help you to measure an angle?
• What’s the same and what’s different about drawing angles of 80˚ and 100˚?
• When you have several angles, is it better to add them first or to subtract them one by one?
• What’s the same about the quadrilaterals? What’s different about the quadrilaterals? Why is a square a special type of rectangle? Why is a rhombus a special type of parallelogram?
• What is a polygon? Can a polygon have a curved line? Name a shape which isn’t a polygon. What makes a polygon irregular or regular? Is a square regular? Are all hexagons regular?