1st Grade Math Question of the Day

1. Circle
2. Square (correct answer)
3. Cone
4. Triangle

Explanation: This question tests 1st grade shape composition and decomposition (CCSS.1.G.2). Shape composition means putting smaller shapes together to make a new, larger shape. For example, two triangles can be arranged to make a square, or two squares can be put next to each other to make a rectangle. The reverse—decomposition—means dividing a shape into smaller parts. The scenario involves Emma putting two triangles together to form a new shape. Choice B is correct because two right-angled triangles can be arranged with their hypotenuses together to make a square. Choice A is a common error where students might think of curved shapes instead of straight-sided ones, often because they confuse 2D and 3D properties or lack visualization skills. To help students: Provide physical pattern blocks or shape manipulatives for hands-on exploration; demonstrate multiple compositions with same shapes (2 triangles can make square OR rectangle depending on arrangement); practice both composition (building up) and decomposition (taking apart); use real-world examples like pizza slices or sandwiches cut in half; draw or trace shapes to show combinations.