standard_description: Understand subtraction as an unknown-addend problem. For example, subtract 10 – 8 by finding the number that makes 10 when added to 8.
problem_activity: Stage 1: Rectangles
Required Preparation
Materials to Gather
Folders
Grid paper
Inch tiles
Materials to Copy
Blackline Masters
Can You Build It Stage 1 Directions

Narrative
One partner builds a rectangle so that their partner can’t see it. They describe the rectangle to their partner who tries to build the same rectangle. Students then compare their rectangles and switch roles. Students may choose to draw their rectangle on grid paper, rather than use inch tiles.
Variation:
Students may use more tiles to build their rectangles or may choose to build shapes made out of two rectangles.
Additional Information
Each group of 2 needs at least 48 inch tiles.


aligns: no