Students meet this one as Shape Detectives: Fun with 2D Shapes, and it spans all three 1st grade geometry standards. They test four shapes against the triangle rule (closed, 3 straight sides, 3 corners), pick which shapes compose a rectangle, name the shape used twice in a hexagon picture, then move to equal shares with a pizza cut into fourths and a rectangle to partition into halves.
1.G.1
“Distinguish between defining attributes (e.g., triangles are closed and three-sided) versus non-defining attributes (e.g., color, orientation, overall size); build and draw shapes to possess defining attributes.”
Part 1 separates defining from non-defining attributes: the callout says size, color and which way a shape turns do not change it.
1.G.2
“Compose two-dimensional shapes (rectangles, squares, trapezoids, triangles, half-circles, and quarter-circles) or three-dimensional shapes (cubes, right rectangular prisms, right circular cones, and right circular cylinders) to create a composite shape, and compose new shapes from the composite shape.”
Questions 3 and 4 are composition problems, ending with two trapezoids joined into a hexagon.
1.G.3
“Partition circles and rectangles into two and four equal shares, describe the shares using the words halves, fourths, and quarters, and use the phrases half of, fourth of, and quarter of. Describe the whole as two of, or four of the shares. Understand for these examples that decomposing into more equal shares creates smaller shares.”
Part 3 uses the words fourth and quarter, and question 6 has students do the partitioning themselves.
A detective rule callout defines a true triangle. Students tick yes or no for Shapes A to D; the key confirms B fails for being open and D for a curved side. Question 2 asks them to draw their own closed triangle.
Question 3 asks which two shapes build a rectangle, with 2 matching triangles among the choices. Question 4 shows a hexagon made from two identical trapezoids and asks what shape was used twice.
Shape diagrams lead into two tasks: naming one share of a pizza cut into 4 equal shares, and drawing one straight line to partition a rectangle into 2 equal shares.
Unit opener
The detective framing sets the vocabulary for the whole geometry unit. Keep 'closed, 3 straight sides, 3 corners' as your class chant.
Catch the classic error
Shape C is a triangle turned upside down. A student who ticks no has confused orientation with shape and needs pattern blocks, not another worksheet.
Exit check
Question 6 on its own tells you who can produce equal shares as well as recognize them. Collect it and sort into two piles.
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