Lesson · Grade 5 · Mathematics
Rotation: Quarter, Half and Three-Quarter Turns
- Grade 5
- Mathematics
- 1 min 15 s
- British Columbia
- BC5-MA-34
A flag on a grid turns clockwise around its foot, point P, by a quarter, a half and a three-quarter turn. A clock hand goes from 12 to 3, 6 and 9 alongside it, and a card adds up the degrees: a full turn is 360°, so 360 ÷ 4 = 90°, 2 × 90 = 180° and 3 × 90 = 270°. The pole is still 3 squares long after each turn, and the four flags end as a pinwheel around P, showing that a rotation keeps a shape's size and only turns it around a fixed point.
Concept: Rotation: turning a shape around a point
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In one sentence
The question this lesson answers
How do we turn a shape around a point?
Point P is the centre of rotation, and it stays still.
Transcript
What the lesson says
How do we turn a shape around a point?
Point P is the centre of rotation, and it stays still.
The flag's pole points straight up from P, and it is 3 squares long.
A full turn goes all the way round, and that is 360 degrees.
A quarter turn clockwise is like a clock hand going from 12 to 3.
A quarter turn is 90 degrees, because 360 divided by 4 is 90.
The pole now points right, and it is still 3 squares long.
A half turn is like a clock hand going from 12 to 6.
That is two quarter turns, so 2 times 90 is 180 degrees.
A three-quarter turn clockwise is like a clock hand going from 12 to 9.
That is three quarter turns, so 3 times 90 is 270 degrees.
Each new flag is the same size and shape, just turned around P.
A rotation turns a shape around a fixed point, like these quarter, half and three-quarter turns.
Curriculum
Where this fits
- British Columbia, Grade 5
Mathematics, Geometry and measurement: single transformationsBC5-MA-34
The outcomes and strands follow the British Columbia curriculum.
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