Grade 1 · Math · Unit

Adding Within 100

6 lessonsabout 3 weeks

The unit ends with three more days: a review day, the unit check, and a day to act on what the check showed.

Unit 6 of 8 in the Grade 1 Math Scope and Sequence

What's included in this unit

6 lessons in teaching order, each with its objective and a teacher note
12 practice pages to print, with an easier and a harder page where available
3 classroom tools for the projector
5 check-up pages to collect

The whole unit in one file

Print every page of the unit at once, with the teacher guide first. The guide has one page per lesson: the objective, what to hand out, and the teacher note.

Teacher guide only (PDF)

The unit file, the teacher guide, and saved pages are included with the Teacher plan.

Your PDF is built in your browser, so it always has the newest version of every page.

Lessons

Lesson 1

Add tens to a number

Children add tens to a two-digit number in their heads, such as 34 + 20, with sums up to 99, and say that only the tens digit changes.

StandardCommon Core 1.NBT.C.4Number and Operations in Base Ten

2 class days

Day 1Teach: The Number Hotel · Practice on paper (Core page)
Day 2Practice and check: Check-up page

Warm up and teach

Open The Number Hotel on the projector.

Practice on paper

Add and Subtract Tens
Core page

Check-up page

One more page of Add and Subtract Tens to collect at the end of the lesson.

Lesson 2

Subtract tens from tens

Children subtract multiples of 10 from multiples of 10 in the range 10 to 90 (70 − 30) by crossing out ten-rods, and explain why 7 tens take away 3 tens leaves 4 tens.

StandardCommon Core 1.NBT.C.6Number and Operations in Base Ten

2 class days

Day 1Teach: The Number Hotel · Practice on paper (Core page)
Day 2Practice and check: Practice on paper (Easier page, Harder page) · Check-up page

Lesson 3

Add ones to a two-digit number

Children add a one-digit number to a two-digit number when the ones stay under ten, such as 32 + 5, and say that the tens do not change.

StandardCommon Core 1.NBT.C.4Number and Operations in Base Ten

2 class days

Day 1Teach: The Number Hotel · Practice on paper (Core page)
Day 2Practice and check: Check-up page

Warm up and teach

Open The Number Hotel on the projector.

Practice on paper

Add and Subtract Ones
Core page

Check-up page

One more page of Add and Subtract Ones to collect at the end of the lesson.

Lesson 4

Add ones and make a new ten

Children add a one-digit number to a two-digit number when the ones make a new ten, such as 27 + 5: they jump to the next ten on the number line first, then jump the rest, and write the steps, 27 + 3 + 2 = 32.

StandardCommon Core 1.NBT.C.4Number and Operations in Base Ten

2 class days

Day 1Teach: Open Number Line · Practice on paper (Core page)
Day 2Practice and check: Practice on paper (Easier page, Harder page) · Check-up page

Warm up and teach

Open Open Number Line on the projector.

Practice on paper

Jump Across the Next Ten
Core page Easier page Harder page

Check-up page

One more page of Jump Across the Next Ten to collect at the end of the lesson.

Lesson 5

Add two two-digit numbers: tens with tens, ones with ones

Children add two two-digit numbers shown as rods and cubes when no new ten is made, such as 34 + 25: they add the tens, then the ones, and write the sum up to 99.

StandardCommon Core 1.NBT.C.4Number and Operations in Base Ten

2 class days

Day 1Teach: Place Value Lab · Practice on paper (Core page)
Day 2Practice: More pages from the maker

Warm up and teach

Open Place Value Lab on the projector.

Practice on paper

Add the Blocks
Core page

Make more

Make more pages like this with the Place Value & Rounding maker.

Lesson 6

Add two two-digit numbers and make a new ten

Children add two two-digit numbers when the ones make a new ten (36 + 28), with a drawing of sticks and dots on a tens-and-ones mat, and tell why the new ten joins the tens.

StandardCommon Core 1.NBT.C.4Number and Operations in Base Ten

2 class days

Day 1Teach: Place Value Lab · Practice on paper (Core page)
Day 2Practice and check: Practice on paper (Easier page, Harder page) · Check-up page

Warm up and teach

Open Place Value Lab on the projector.

Practice on paper

Add and Make a New Ten: Tens-and-Ones Mat
Core page Easier page Harder page

Check-up page

One more page of Add and Make a New Ten: Tens-and-Ones Mat to collect at the end of the lesson.

Teacher note

Common mistakes: Children add each column and write both totals side by side, so 36 + 28 becomes 514 (5 tens, 14 ones). Others circle ten dots and forget to draw the new stick, or draw it and still count the circled dots as ones.
Words to use: On the Place Value Lab, build 36 with "Add a ten" and "Add a one." Then add 28 more: two tens and eight ones. "How many ones now? 14. Can we write 14 in the ones place?" The lab asks, "Ten ones! Can you make a ten?" Tap "Make a ten!" and say: "Ten ones make one ten. It joins the tens: 6 tens and 4 ones, 64." Do the same problem on the board with sticks and dots, the dots in rows of five: circle ten dots, draw one new stick, and ask a child to tell why you drew it.
What to watch for: On the easier page, both numbers are drawn on the mat, the second under the first (in green); the child circles ten dots, draws the new stick, and counts. On the page for everyone, the mat is empty: the child draws both numbers first, and every problem makes a new ten. On the harder page, two of the six problems make no new ten, so the child has to look before circling. In the boxes under the mat, ten circled dots count as one ten: 6 tens and 4 ones, not 5 tens and 14 ones. When the ones make exactly ten (41 + 29), the child writes 7 tens and 0 ones; watch for an empty ones box.

Unit check: before and after

Two short paper checks made from this unit's own worksheets. Give Check A before you teach the unit and Check B after it, and you can see what changed. Each part belongs to one lesson.

Part 1: Lesson 1, Add tens to a number (2 tasks)
Part 2: Lesson 2, Subtract tens from tens (1 task)
Part 3: Lesson 3, Add ones to a two-digit number (2 tasks)
Part 4: Lesson 5, Add two two-digit numbers: tens with tens, ones with ones (1 task)
Part 5: Lesson 6, Add two two-digit numbers and make a new ten (2 tasks)

Not in the check: Lesson 4. Worksheets that cannot be split into single tasks are left out.

Check A (PDF) · 2 pages Check B (PDF) · 2 pages

Printing a check counts as a download, like any worksheet.

Answer key A Answer key B Teacher pages: points, class record, and what to do next

The answer keys and the teacher pages come with the paid Teacher plan.

This is a classroom check of this unit's lessons. It is not a standardized test, and its points are not a grade.

Unit checks