1.3.A

Math1st GradeNumber and operations

The Standard

use concrete and pictorial models to determine the sum of a multiple of 10 and a one-digit number in problems up to 99

Texas Essential Knowledge and Skills for Mathematics

Teacher's field guide

What This Standard Means

What Students Need to Do

Students build or draw a number made of full tens, then add up to nine ones. They connect the model to an equation and find the total without regrouping.

What Mastery Looks Like

A student can build or draw full tens and add separate ones. The student writes the correct equation and explains that the number of tens stays the same.

Common Misconceptions

Students may add the digit to the number of tens, saying 40 + 3 equals 70. They may also count ten-rods as single ones or reverse the tens and ones when writing the total.

How to Assess It

Give students the prompt: “Solve 60 + 7. Draw a model, write the total, and label the tens and ones.”

Lesson moves

Ways to Teach It

  1. Give students ten-rods and unit cubes to build 40 + 6, then draw the model and write 46.

  2. Ask, “Mia says 70 + 5 equals 75. How could a drawing prove her answer?”

  3. Partners draw one tens card and one digit card, build the sum, and record the equation on a whiteboard.

  4. Bundle straws into groups of ten, add loose straws, and count the total as classroom supplies.

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