standard_description: Add within 100, including adding a two-digit number and a one-digit number, and adding a two-digit number and a multiple of 10, using concrete models or drawings and strategies based on place value, properties of operations, and/or the relationship between addition and subtraction; relate the strategy to a written method and explain the reasoning used. Understand that in adding two-digit numbers, one adds tens and tens, ones and ones; and sometimes it is necessary to compose a ten.
problem_activity: Stage 1: Any Way
Required Preparation
Materials to Gather
Collections of objects
Materials to Copy
Blackline Masters
Sort and Display Stage 1 Recording Sheet

Narrative
Students sort 10–20 objects into two or three categories and then show how they sorted. Provide students with a group of items that will be interesting for them to work with such as:
pattern blocks
connecting cubes
counters
combination of the blocks, cubes, and counters
sets of books
Students then show their representation to a partner and ask questions that can be answered about their collection of objects.
Additional Information
Create collections of 10–20 objects with up to three attributes by which to sort.


aligns: no