standard_description: Mentally add 10 or 100 to a given number 100–900, and mentally subtract 10 or 100 from a given number 100–900.
problem_activity: Stage 1: Groups of Objects
Required Preparation
Materials to Gather
Collections of objects
Connecting cubes
Materials to Copy
Blackline Masters
Less, Same, More Mat

Narrative
Students choose a collection of objects and place the objects in the box at the top of the mat. They complete the mat to show groups that have fewer, the same, or more objects than the original amount.
Additional Information
Give at least 2 collections of between 2 and 9 objects per group of 2.


aligns: no