standard_description: Subtract multiples of 10 in the range 10-90 from multiples of 10 in the range 10-90 (positive or zero differences), 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.
problem_activity: Stage 1: Choose Your Unit
Required Preparation
Materials to Gather
Base-ten blocks
Connecting cubes
Paper clips (2-inch)
Materials to Copy
Blackline Masters
Estimate and Measure Stage 1 Recording Sheet

Narrative
Students choose an object and a familiar unit to measure it with. They estimate the length of the object and then measure to see the actual length to the nearest whole unit.
Variation:
Students may use base-ten cubes and add the length of two objects to practice adding within 100.
Additional Information
Gather or identify objects of various lengths that are less than 20 units (pencils, markers, books, glue, scissors, shoe, tape dispenser, side of desk).


aligns: no