standard_description: Given a two-digit number, mentally find 10 more or 10 less than the number, without having to count; explain the reasoning used.
problem_activity: Stage 1: Two-digit Numbers
Required Preparation
Materials to Gather
Number cards 0–10
Materials to Copy
Blackline Masters
Mystery Number Stage 1 Directions

Narrative
Students pick two cards and make a mystery two-digit number. Students give clues based on the sentence starters.


aligns: no