Montana Math MT.1.NBT.4

Math1st GradeNumber and Operations in Base Ten

The Standard

Build a foundation for addition within 100 by: Adding two-digit to one-digit numbers, and Adding multiples of 10 to two-digit numbers.

2026 Montana Mathematics Content Standards

Teacher's field guide

What Students Need to Do: Students add a one-digit number or a multiple of 10 to a two-digit number. They use tens and ones to show what changes, including when ten ones make a new ten.
What Mastery Looks Like: A student can show 28 + 5 = 33 by making a new ten from 13 ones. They can show 34 + 20 = 54 by adding two tens and keeping four ones.
Common Misconceptions: Some students treat 20 as two ones and say 34 + 20 = 36. Others write 213 for 28 + 5 because they do not trade 10 ones for a ten.
How to Assess It: Exit ticket: Draw tens and ones to solve 28 + 5 and 34 + 20. Write what changed in each problem.

Lesson moves

Give students base-ten blocks to build 28 + 5, trade ten unit cubes for a ten rod, and record 33.
Ask partners to sketch 34 + 20 and explain why the ones digit stays the same.
Have students match cards showing 26 + 3, 26 + 30, and 26 + 7 to answer cards showing 29, 56, and 33.
Tell students a class shelf has 38 books and receives 20 more; have them draw tens and ones to find the new total.

Free download

$Preview of the MT.1.NBT.4 printable worksheet$

A ready-to-print activity worksheet aligned to MT.1.NBT.4, with an answer key for the teacher on its own page. No account needed.

PDF, US Letter, prints cleanly in black and white.

Keep exploring

Grade, subject, topic, and the complete standard are prefilled. Create one free, no account needed.