# Addition and Subtraction Within 100

*30 minutes, 3 stages*

You are learning to add and subtract numbers up to 100 ([Outcome](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/29844)). This helps you count things, measure things, and solve everyday problems ([Understanding](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/29851)).

## Stage 1: Warm-up (8 min)

Students investigate addition and subtraction within 100.

Write the answers to these addition facts. Addends (the numbers you add) go up to 10 ([Skills](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/29852)).

1. 4 + 6 = ___
2. 7 + 5 = ___
3. 9 + 8 = ___
4. 6 + 6 = ___
5. 3 + 9 = ___

Now write the matching subtraction fact for each one. For example, if 4 + 6 = 10, write 10 − 6 = 4.

6. ___
7. ___
8. ___
9. ___
10. ___

## Stage 2: Build and solve (14 min)

Think of 100 as groups of ten ([Skills](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/29848)). Draw 10 tally sticks in a bundle to picture one ten. You do not need to draw all of these, just picture the bundles in your head.

Solve these two-digit problems. Try making a ten or using doubles to help you ([Knowledge](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/29850)).

1. 34 + 25 = ___
2. 48 + 26 = ___
3. 63 − 27 = ___
4. 90 − 45 = ___
5. 17 + 38 = ___

Now compose 100 in three different ways. Fill in the blanks so each equation is true ([Skills](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/29848)).

6. 40 + ___ = 100
7. ___ + 30 + 20 = 100
8. 100 − ___ = 55

Solve this story problem. Show your work ([Skills](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/29852)):

9. Maya has 48 stickers. She gives away 19 stickers. How many stickers does Maya have now?

Solve this missing-number problem ([Skills](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/29852)):

10. 26 + ___ = 61

## Stage 3: Check your work (8 min)

Pick three problems from Stage 2 (numbers 1 to 5) and check each answer using the opposite operation ([Skills](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/29852)). For example, check 34 + 25 = 59 by solving 59 − 25. Write your checks below.

Check for problem ___: ___
Check for problem ___: ___
Check for problem ___: ___

Now try adding three numbers in a different order to see if the sum stays the same ([Knowledge](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/29846)).

Solve: 20 + 35 + 10 = ___
Solve again in a new order: 35 + 10 + 20 = ___

Are the two sums the same? Write yes or no: ___

## Self-check

1. What is one strategy you used today to add two-digit numbers? (Example: making a ten, using doubles.)
2. Pick one subtraction answer from Stage 2. How do you know it is correct?
3. Does the order you add numbers change the sum? How do you know?

---
*AILI student homework · language en · model claude-sonnet-5 · generated 2026-09-17 · id 55713a99-d684-4fa6-855d-b70f28b00d69*

### Sources

- node:n1: Mathematics › Mathematics (K–6) › Grade 2 › Number: Quantity is measured with numbers that enable counting, labelling, comparing, and operating. (https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/29843)
- node:n2: Mathematics › Mathematics (K–6) › Grade 2 › Number: Quantity is measured with numbers that enable counting, labelling, comparing, and operating. › How can addition and subtraction be interpreted? (https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/29844)
- node:n3: Mathematics › Mathematics (K–6) › Grade 2 › Number: Quantity is measured with numbers that enable counting, labelling, comparing, and operating. › How can addition and subtraction be interpreted? › Students investigate addition and subtraction within 100. (https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/29846)
- node:n4: Mathematics › Mathematics (K–6) › Grade 2 › Number: Quantity is measured with numbers that enable counting, labelling, comparing, and operating. › How can addition and subtraction be interpreted? › Students investigate addition and subtraction within 100. (https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/29848)
- node:n5: Mathematics › Mathematics (K–6) › Grade 2 › Number: Quantity is measured with numbers that enable counting, labelling, comparing, and operating. › How can addition and subtraction be interpreted? › Students investigate addition and subtraction within 100. (https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/29847)
- node:n6: Mathematics › Mathematics (K–6) › Grade 2 › Number: Quantity is measured with numbers that enable counting, labelling, comparing, and operating. › How can addition and subtraction be interpreted? › Students investigate addition and subtraction within 100. (https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/29850)
- node:n7: Mathematics › Mathematics (K–6) › Grade 2 › Number: Quantity is measured with numbers that enable counting, labelling, comparing, and operating. › How can addition and subtraction be interpreted? › Students investigate addition and subtraction within 100. (https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/29852)
- node:n8: Mathematics › Mathematics (K–6) › Grade 2 › Number: Quantity is measured with numbers that enable counting, labelling, comparing, and operating. › How can addition and subtraction be interpreted? › Students investigate addition and subtraction within 100. (https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/29851)
- node:n9: Mathematics › Mathematics (K–6) › Grade 2 › Number: Quantity is measured with numbers that enable counting, labelling, comparing, and operating. › How can addition and subtraction be interpreted? › Students investigate addition and subtraction within 100. (https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/29852)
- node:n10: Mathematics › Mathematics (K–6) › Grade 2 › Number: Quantity is measured with numbers that enable counting, labelling, comparing, and operating. › How can addition and subtraction be interpreted? › Students investigate addition and subtraction within 100. (https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/29850)
- node:n11: Mathematics › Mathematics (K–6) › Grade 2 › Number: Quantity is measured with numbers that enable counting, labelling, comparing, and operating. › How can addition and subtraction be interpreted? › Students investigate addition and subtraction within 100. (https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/29848)
- node:n12: Mathematics › Mathematics (K–6) › Grade 2 › Number: Quantity is measured with numbers that enable counting, labelling, comparing, and operating. › How can addition and subtraction be interpreted? (https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/29844)
- node:n13: Mathematics › Mathematics (K–6) › Grade 2 › Number: Quantity is measured with numbers that enable counting, labelling, comparing, and operating. › How can addition and subtraction be interpreted? › Students investigate addition and subtraction within 100. (https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/29847)
- node:n14: Mathematics › Mathematics (K–6) › Grade 2 › Number: Quantity is measured with numbers that enable counting, labelling, comparing, and operating. › How can addition and subtraction be interpreted? › Students investigate addition and subtraction within 100. (https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/29851)
- node:n15: Mathematics › Mathematics (K–6) › Grade 2 › Number: Quantity is measured with numbers that enable counting, labelling, comparing, and operating. › How can addition and subtraction be interpreted? › Students investigate addition and subtraction within 100. (https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/29846)