Adding Within 20
Part of the Math for Young Minds curriculum — designed for neurodivergent students, grounded in real-world examples.
📋 Session plan (for teachers)
Session 4 — Adding within 20
Grade 1 · Math for Young Minds Total time: ~19 minutes Common Core: 1.OA.C.6 Today's idea: When a number is almost 10, we can make 10 first. Then adding is easy.
What students will be able to do
By the end of this session, the student can:
- Add two numbers when the answer is more than 10 but no more than 20.
- Use the make 10 trick (like 8 + 5 → 8 + 2 + 3 → 10 + 3 = 13).
- Read and write addition sentences with sums up to 20.
Materials
- 20 counters per pair of students
- Two ten-frame mats per pair (side by side)
- Worksheet (one per student)
- Pencil
Substitution: No counters? Use pasta, beans, buttons, or pennies. No printed ten-frames? Draw two 2×5 grids on paper.
New words
| Word | Meaning we use in class |
|---|---|
| make 10 | A trick where we move a few from one number to fill the first ten. |
That's the entire vocabulary for today. No other terms.
Heads-up — common confusions
- Counting on by 1s. A child may add 8 + 5 by counting "9, 10, 11, 12, 13" on fingers. That works, but it's slow. Today we want them to make 10 first.
- Losing track of the move. When moving 2 over to fill the ten, kids forget how many they had left. Slow them down. "You moved 2. How many are still waiting?"
- Mixing up the order. A child might fill the second ten-frame first. Remind them: first ten-frame fills up first.
Plan
1 · Hello & today's idea — 2 min
"Today we're adding bigger numbers — answers all the way up to 20. We have a trick. It's called make 10."
Hold up two ten-frame mats side by side.
"First we fill this ten-frame all the way up. Then the extras go over here. Ten plus a few extras is easy to count."
2 · Hands-on explore — 6 min
Give each pair 20 counters and two ten-frame mats.
Problem 1 (together): 8 + 5
"Put 8 counters on the first ten-frame. Now put 5 more counters next to it."
Walk around. Most pairs will have 8 in the first frame with 2 empty spots.
"Look — the first frame still has room for 2 more. Slide 2 from your pile of 5 over to fill it up."
Pause. Let them do it.
"Now your first ten-frame is full. That's 10. How many are left over?"
Wait. "Three. So 10 and 3 more is… 13. 8 + 5 = 13."
Write 8 + 5 = 13 on the board.
"That's the make-10 trick. We moved 2 over to fill the ten. Then we just added the extras."
3 · Connect to the math — 3 min
Stand at the front. Write 8 + 5 on the board.
"Watch how I write the trick."
Slowly write:
- 8 + 5
- 8 + 2 + 3
- 10 + 3
- = 13
"I broke the 5 into 2 and 3. The 2 fills the ten. The 3 is left over. Ten plus three is thirteen."
Point to each line. "Same answer. Easier to see."
4 · Practice with support — 6 min
Pass out the worksheet. Students keep their counters and ten-frames.
Problem 2 (solo): 9 + 4
"Put 9 on the first frame. How many empty spots? Just 1. Slide 1 over. Now you have 10 and… how many left?"
Walk around. Listen for 13.
Problem 3 (solo): 7 + 6
"Put 7 on the first frame. How many empty spots?" Wait for 3. "Slide 3 over. Now 10 and 3 more. What's the answer?"
Listen for 13.
Problem 4 (stretch): 8 + 7 — show your work
"Try this one without me. Use the make-10 trick. Write it down like I did on the board."
Look for: 8 + 2 = 10, then 10 + 5 = 15.
If a child is stuck, kneel beside them. Point to the ten-frame. "How many more would fill it up?"
5 · What we did + Try at home — 2 min
"Today you learned the make 10 trick. When one number is close to 10, move a few over to fill the ten. Then add the extras."
Hold up 8 fingers on one hand, 5 on the other. "8 plus 5. Move 2 over… 10 and 3 is 13."
"At home tonight: find two piles of something. Maybe spoons and forks. Or grapes. Or crayons. Put them together. Was the total more than 10? Use your fingers to check."
Observation rubric — what to notice in this session
Use this during the session, not as a test. One observation per student is plenty.
| Where the student is | What you'd see |
|---|---|
| Developing | Counts on by 1s using fingers. Doesn't yet move counters to fill the ten. Needs your hand to guide the move. |
| Using | Fills the first ten-frame, slides extras over to make 10, says "10 and 3 is 13." Can write the addition sentence. |
| Extending | Uses make-10 in their head without counters. Notices that many of today's answers are 13. |
No fail state. "Developing" today is "using" next week.
What's next (Session 5)
In Session 5 — Comparing two-digit numbers, we look at two 2-digit numbers and figure out which is bigger — by checking the tens first.
✏️ Worksheet (for students)
Math for Young Minds · Grade 1
4 · Adding within 20
[ Hello ] → [ Explore ] → [ Connect ] → [ Practice ← we are here ] → [ Try at home ]
My name: _____________________________
Today
Fill the first ten-frame. Then count the extras. 10 + extras = answer.
Example we did together
8 + 5 = ?
Move 2 from the 5 to fill the first ten-frame. Now it's 10 + 3.
First ten-frame: Second ten-frame:
┌────┬────┬────┬────┬────┐ ┌────┬────┬────┬────┬────┐
│ ● │ ● │ ● │ ● │ ● │ │ ● │ ● │ ● │ │ │
├────┼────┼────┼────┼────┤ ├────┼────┼────┼────┼────┤
│ ● │ ● │ ● │ ● │ ● │ │ │ │ │ │ │
└────┴────┴────┴────┴────┘ └────┴────┴────┴────┴────┘
10 + 3 = 13
8 + 5 = 13
Problem 1 — together
8 + 5 = ? Fill the first ten-frame. Put extras in the second.
┌────┬────┬────┬────┬────┐ ┌────┬────┬────┬────┬────┐
│ │ │ │ │ │ │ │ │ │ │ │
├────┼────┼────┼────┼────┤ ├────┼────┼────┼────┼────┤
│ │ │ │ │ │ │ │ │ │ │ │
└────┴────┴────┴────┴────┘ └────┴────┴────┴────┴────┘
➤ 8 + 5 = _______
Problem 2 — on your own
9 + 4 = ?
┌────┬────┬────┬────┬────┐ ┌────┬────┬────┬────┬────┐
│ │ │ │ │ │ │ │ │ │ │ │
├────┼────┼────┼────┼────┤ ├────┼────┼────┼────┼────┤
│ │ │ │ │ │ │ │ │ │ │ │
└────┴────┴────┴────┴────┘ └────┴────┴────┴────┴────┘
➤ 9 + 4 = _______
Problem 3 — on your own
7 + 6 = ?
┌────┬────┬────┬────┬────┐ ┌────┬────┬────┬────┬────┐
│ │ │ │ │ │ │ │ │ │ │ │
├────┼────┼────┼────┼────┤ ├────┼────┼────┼────┼────┤
│ │ │ │ │ │ │ │ │ │ │ │
└────┴────┴────┴────┴────┘ └────┴────┴────┴────┴────┘
➤ 7 + 6 = _______
Problem 4 — stretch
Use make 10 for 8 + 7. Show your work.
┌─────────────────────────────────────────────────────────┐
│ │
│ 8 + ____ = 10 │
│ │
│ 10 + ____ = ____ │
│ │
│ │
│ So 8 + 7 = ____ │
│ │
└─────────────────────────────────────────────────────────┘
Today's words
| word | what it means |
|---|---|
| make 10 | a strategy where we move a few from one number to fill the first ten |
🏠 Try at home tonight
Find two piles of something at home. Put them together. Was the total more than 10? Use your fingers to check.
- 7 fingers up + 4 more fingers ✋✋
- 8 spoons + 6 forks 🥄🍴
- 9 grapes + 5 grapes 🍇
- 7 crayons + 5 crayons ✏️
Make 10 first. Then count the extras.
🏠 Family guide (for parents)
Math for Young Minds · Grade 1 · Session 4
Tonight: put two piles together and see what you get
What your child did today
In class today, we practiced adding numbers when the answer is bigger than 10.
We used two ten-frame mats side by side, with counters. The big idea: when one number is close to 10, we can move a few counters over to fill the first ten-frame, then count what's left in the second.
For example, 8 + 5 becomes 8 + 2 + 3, which is 10 + 3, which is 13.
It's the same answer either way — but filling up to 10 first makes the counting easier.
Why this matters
Adding past 10 is the first time kids meet numbers that "cross over." Counting on by 1s works, but it gets slow and shaky fast. The make 10 strategy is a thinking habit: find the friendly number first, then finish. That same habit shows up later in subtraction, in place value, and in mental math for the rest of school. We are not in a rush. Understanding comes before speed, and speed shows up on its own once the thinking feels solid.
🏠 Try this tonight (1 minute)
Find two small piles of something at home. Put them together. Ask: was the total more than 10? Use fingers to check.
| Easy starters |
|---|
| 7 fingers up + 4 more fingers |
| 8 spoons + 6 forks |
| 9 grapes + 5 grapes |
| 7 crayons + 5 crayons |
The script:
"Here's one pile, here's another. How many altogether? Can you fill up to 10 first?"
If they start counting by 1s, that's okay. Gently nudge:
"How many more would it take to get to 10? Then how many extra are left?"
Words your child is learning
- make 10 — a strategy where we move a few from one number to fill the first ten
That's the whole list for today.
If your child says…
"This is easy — I can just count."
Lovely. Ask them to try 8 + 7 using the make-10 trick instead. Counting by 1s gets the right answer, but the trick is faster and builds the thinking they'll need next year. Both ways are welcome.
"This is hard. I keep losing track."
Very normal. The tricky part is remembering how many you moved across. Slow down and use fingers or small objects — one hand for the first ten, the other hand for the extras. No timed tests here. Accuracy first.
"I don't want to."
That's okay. Try later with something they like — grapes at snack time, toy cars on the floor, socks coming out of the laundry. Math at this age should feel like noticing the world.
What's next
In Session 5, we move to comparing two-digit numbers. We'll look at two numbers and figure out which is bigger — by checking the tens place first.
Thanks for taking a minute tonight. These small kitchen-table moments are where math lives.
— Math for Young Minds
🔑 Cheat sheet (visual)
➕ Make 10 to add
The big idea
8 + 5 = ?
move 2 over → fill the ten → count the rest
8 + 5 = 8 + 2 + 3 = 10 + 3 = 13
Picture it: 8 + 5
Start:
Ten-frame A Ten-frame B
┌──┬──┬──┬──┬──┐ ┌──┬──┬──┬──┬──┐
│🔵│🔵│🔵│🔵│🔵│ │🔴│🔴│🔴│🔴│🔴│
├──┼──┼──┼──┼──┤ ├──┼──┼──┼──┼──┤
│🔵│🔵│🔵│ │ │ │ │ │ │ │ │
└──┴──┴──┴──┴──┘ └──┴──┴──┴──┴──┘
8 5
Move 2 over → make 10:
┌──┬──┬──┬──┬──┐ ┌──┬──┬──┬──┬──┐
│🔵│🔵│🔵│🔵│🔵│ │🔴│🔴│🔴│ │ │
├──┼──┼──┼──┼──┤ ├──┼──┼──┼──┼──┤
│🔵│🔵│🔵│🔴│🔴│ │ │ │ │ │ │
└──┴──┴──┴──┴──┘ └──┴──┴──┴──┴──┘
10 3
↑
10 + 3 = **13**
Try it: 9 + 4
┌──┬──┬──┬──┬──┐ ┌──┬──┬──┬──┬──┐
│🔵│🔵│🔵│🔵│🔵│ │🔴│🔴│🔴│🔴│ │
├──┼──┼──┼──┼──┤ ├──┼──┼──┼──┼──┤
│🔵│🔵│🔵│🔵│🔴│ │🔴│🔴│🔴│ │ │
└──┴──┴──┴──┴──┘ └──┴──┴──┴──┴──┘
10 3
9 + 1 = 10, then 10 + 3 = 13 ✨
Try it: 7 + 6
┌──┬──┬──┬──┬──┐ ┌──┬──┬──┬──┬──┐
│🔵│🔵│🔵│🔵│🔵│ │🔴│🔴│🔴│ │ │
├──┼──┼──┼──┼──┤ ├──┼──┼──┼──┼──┤
│🔵│🔵│🔴│🔴│🔴│ │ │ │ │ │ │
└──┴──┴──┴──┴──┘ └──┴──┴──┴──┴──┘
10 3
7 + 3 = 10, then 10 + 3 = 13 ✨
How to read it
8 + 5 = 13
↑ ↑ ↑
part part total
The Big Rules
✅ Fill the first ten-frame FIRST. ✅ Move just enough over to make 10. ✅ Then add what's left.
❌ Don't count by 1s — too slow! ❌ Don't forget how many you moved.
🌟 Try in your head: 8 + 7
8 + 2 = 10
10 + ? = ?
8 + 2 = 10
10 + 5 = 15 ✅