# Marking Guide: Addition and Subtraction Within 100

## Task

Students present a labelled model or report on addition and subtraction within 100.

## Curriculum alignment

Students investigate addition and subtraction within 100 ([Outcome](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/29844)), part of the organizing idea that quantity is measured with numbers that enable counting, labelling, comparing, and operating ([Guiding question](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/29843)).

The task draws on these outcomes:

- Recall addition facts with addends to 10 and related subtraction facts, and add and subtract within 100 ([Skills](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/29852), [Skills](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/29852)).
- Show that a sum can be composed in more than one way, including with more than two addends ([Understanding](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/29847), [Skills](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/29848)).
- Use strategies such as making multiples of ten and using doubles ([Knowledge](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/29850), [Knowledge](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/29850)).
- Show that addition and subtraction can represent countable quantities or measurable lengths ([Understanding](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/29851), [Understanding](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/29851)).
- Verify a sum or difference using inverse operations ([Skills](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/29852)).

## Rubric

| Criterion | Beginning | Developing | Proficient | Exemplary |
|---|---|---|---|---|
| Number facts and computation | Adds or subtracts within 100 with many errors, even with support. | Adds and subtracts within 100 with some errors; needs prompts for facts to 10. | Adds and subtracts within 100 correctly, using facts to 10 and related subtraction facts ([Skills](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/29852)). | Adds and subtracts within 100 correctly and quickly, and checks answers using inverse operations ([Skills](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/29852)). |
| Composing sums | Shows only one way to make a sum, or the sum is incorrect. | Shows a sum made two ways with adult help. | Shows a sum composed in more than one way, including with more than two addends ([Skills](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/29848), [Understanding](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/29847)). | Shows several ways to compose the same sum, including three or more addends, without help ([Skills](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/29848)). |
| Strategy use | Uses counting by ones only, with no other strategy shown. | Attempts a strategy such as making tens, but applies it inconsistently. | Uses a clear strategy, such as making multiples of ten or using doubles, to solve problems ([Knowledge](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/29850)). | Explains why a strategy works and chooses it deliberately for the numbers involved ([Knowledge](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/29850), [Knowledge](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/29846)). |
| Representing quantities and problems | Model or report does not connect numbers to real quantities or lengths. | Model shows a quantity or length, but the connection to the number sentence is unclear. | Model or report clearly shows addition or subtraction of countable quantities or lengths ([Understanding](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/29851)). | Model or report clearly shows quantities or lengths and solves a problem using them ([Skills](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/29852), [Understanding](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/29851)). |

## Scoring

Score each of the four criteria as Beginning (1), Developing (2), Proficient (3), or Exemplary (4). Add the four scores for a total out of 16.

- 4 to 6: Beginning overall
- 7 to 10: Developing overall
- 11 to 13: Proficient overall
- 14 to 16: Exemplary overall

A score of Beginning on any single criterion signals a specific gap to address, even if the total lands in a higher band.

## Notes for the teacher

- Look for the strategy the student names or draws, not just the final answer. A correct sum with no visible strategy still sits at Developing for that criterion.
- Accept any valid way of composing a sum, including with three or more addends. Do not require a specific method ([Skills](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/29848)).
- Let students explain their model orally if writing is a barrier. Score the math shown, not the writing quality.
- Keep a few sample models at each level to compare against, so scoring stays consistent across the class.

---
*AILI marking guide · language en · model claude-sonnet-5 · generated 2026-09-17 · id e4c53230-2bda-4f58-8062-739bb0710bc7*

### 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)