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Partial Progress - Circles (browser only)
Names Of Angles
Objectives
To recognise angles larger and smaller than 90º and to be able to classify the angle.
To understand that the angle of a full turn is 360º.
Resources
Abacus 4 Textbook 2 | Scanner or photocopier | Ruler | Squared paper | Circle (e.g. from a set of 2D shapes)
Today's Lesson
Main Activity
Draw a circle (you could draw round a circle from a set of 2D shapes) and divide it into quarters with a ruler by drawing lines down the middle from top to bottom and from side to side. These lines can be accurately constructed by folding the circle in half, then half again.
Ask your student to remind you of the name of the angle made by one of the quarters. Hopefully they will recall the name ‘right angle’. Your student may also remember that the measurement of a right angle is ninety degrees, 90º.
Point out that now we have recognised this, we can see that there are four 90˚ angles at the centre of the circle, and if we work out 90 x 4 = 360, we can see that the angles in a circle always add up to 360º.
Also show your student, using the lines drawn on the circle, how the measurement of the angle of a straight line is exactly half of 360, therefore, 180º (or 2 x 90˚).
Now draw a few different angles, using a ruler, and ask your student if they are larger or smaller than a right angle.
Watch the 'Angles' video.
Explain to your student that any angle smaller than a right angle, or less than 90˚, is called an acute angle. If the angle is greater than 90º but less than 180˚, we call this an obtuse angle.
Turn to page 31 in Abacus 4 Textbook 2.
Scan or copy the page, so that your student can have the images of the angles directly opposite the chart they will be writing on. Copy the chart as shown in the textbook. Explain to your student that they will be writing about each shape and noting the number of different angles within the shape.
Turn to page 32 and scan or copy the page, so your student may write directly on the paper. Ask your student to write ‘acute angle’, ‘right angle’ or ‘obtuse angle’ underneath each shape, for the angle marked. Ask your student to complete the page.