Composing Shapes
Compose two-dimensional shapes (rectangles, squares, trapezoids, triangles, half-circles, quarter-circles) to create composite shapes, and compose new shapes from the composite shape
What a learner can do afterwards
- Combine two triangles to form a rectangle or larger triangle
- Put together half-circles and quarter-circles to form circles or new shapes
- Decompose a composite shape and describe which simpler shapes make it up
- Names triangles, circles, rectangles, squares and trapezoids by their straight side counts.
1 · Read
You already know how to put two shapes together to make a new one. Now you will go further. You can put together shapes like triangles, half-circles, and quarter-circles to build new shapes. You can even use the new shape you just built to build something even bigger. Four same-size quarter-circles fit together to make one whole circle, just as two half-circles do.
Leo has two same-size triangles, each with one square corner like the corner of a book. He flips one over so their long slanted sides touch with no gaps. Now the two triangles together make one rectangle.
A shape you build, like Leo's rectangle, is called a composite shape. You can use a composite shape like any other piece. Put a triangle on top of the rectangle, and you have built a house. That rectangle uses 2 triangles. Triangles have 3 straight sides. Trapezoids and rectangles have 4. Circles have none.
When you see a shape, look for the smaller shapes inside it: which flat shapes made this one?
Put simple shapes together to build new shapes, then use those new shapes to build something even bigger.
The rewritten reading was written for this dataset.
2 · Watch
Take it off screen
Where it sits
Learn first
This opens up
Where this leads
Jobs that lean on this skill. Follow one to see everything it is built on.
16 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.