standard_description: Represent addition, subtraction, multiplication, and conjugation of complex numbers geometrically on the complex plane; use properties of this representation for computation. For example, (-1 + Ö3i)^(3) = 8 because (-1 + Ö3i) has modulus 2 and argument 120°.
problem_activity: Stage 2: Subtract from 20
Required Preparation
Materials to Gather
Number cards 0–10
Materials to Copy
Blackline Masters
How Close? Stage 2 Recording Sheet

Narrative
Before playing, students remove the cards that show the number 10 and set them aside.
Each student picks 4 cards and chooses 2 or 3 to subtract from 20 to get close to 0. The student whose difference is closest to 0 wins a point for the round. Students pick new cards so that they have 4 cards in their hand and then start the next round.


aligns: no