Lesson · Grade 6 · Mathematics
Rotations: Turning a Shape About a Point
- Grade 6
- Mathematics
- 1 min 10 s
- British Columbia
- BC6-MA-41
Triangle ABC turns 90° clockwise about a centre of rotation P. Corner A, 5 units left of P, swings like a clock hand from 9 to 12 and lands 5 units above P, and then the whole triangle turns the same way. The video shows that every corner moves along a circle around P, stays the same distance from it and turns through the same 90°, so the image is the same size and shape, only turned.
Concept: Rotations
Anyone can watch two lessons on the website without an account. Signing in is free, no payment and no card, and opens three a day; Plus has no limit.
Loading
In one sentence
The question this lesson answers
A rotation turns a shape around a fixed point, called the centre of rotation.
Let us rotate triangle A B C 90 degrees clockwise about point P.
Transcript
What the lesson says
A rotation turns a shape around a fixed point, called the centre of rotation.
Let us rotate triangle A B C 90 degrees clockwise about point P.
To describe a rotation, we give its centre, its angle and its direction.
Corner A is 5 units to the left of P.
Turn this line a quarter turn clockwise, like a clock hand going from 9 to 12.
So A prime is 5 units straight above P.
Now turn the whole triangle the same way, keeping P fixed.
The new triangle, A prime B prime C prime, is called the image.
Each corner moved along a circle, so it stays the same distance from P.
Each corner also turned through the same 90 degrees.
The image is the same size and shape as the triangle, just turned.
A rotation turns every point through the same angle about the centre.
Curriculum
Where this fits
- British Columbia, Grade 6
Mathematics, Geometry and measurement: combinations of transformationsBC6-MA-41
Previous: Reflections: Same Distance, Other Side of the MirrorNext: Combining Two Transformations
- British Columbia, Grade 7
Mathematics, Geometry and measurement: combinations of transformationsBC7-MA-61
Previous: Reflections: Same Distance, Other Side of the MirrorNext: Combining Two Transformations
This lesson is also listed in Grade 7.
The outcomes and strands follow the British Columbia curriculum.
Keep going
1 min 12 s3:15 p.m. or 15:15? Morning, afternoon and the 24-hour clock
Grade 4 · 1 min 12 s
1 min 26 s3D Objects: Faces, Edges and Vertices
Grade 3 · 1 min 26 s
1 min 21 sArea and Perimeter: What Is the Difference?
Grade 5 · 1 min 21 s
1 min 5 sArea of a Circle from the Radius or the Diameter
Grade 7 · 1 min 5 s
1 min 14 sArea of a Parallelogram: Cut and Slide into a Rectangle
Grade 6 · 1 min 14 s
1 min 18 sArea of a Rectangle: Count the Squares, Then Multiply
Grade 5 · 1 min 18 s
1 min 16 sArea of a Trapezoid: Two Copies Make a Parallelogram
Grade 6 · 1 min 16 s
1 min 19 sArea of a Triangle: Half of a Parallelogram
Grade 6 · 1 min 19 s
- All Grade 6 Mathematics lessons
- Teachers: the maths worksheets for Grade 6 are in the dashboard, each with a worked example and a proven answer key.
- Try the graph paper, free for everyone, no account needed.
- Create a free account to watch three lessons a day, no payment and no card.