# Addition and Subtraction Within 100: Marking Guide

## 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)). The rubric assesses:

- Recall and apply addition and subtraction number facts with addends to 10 and related subtraction facts ([Skills](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/29852)).
- Add numbers up to a sum of 100 and subtract numbers with a maximum minuend of 100 ([Skills](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/29852)).
- Verify a sum or difference using inverse operations ([Skills](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/29852)).
- Solve problems using addition and subtraction of countable quantities or measurable lengths ([Skills](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/29852)).

## Rubric

| Criterion | Beginning | Developing | Proficient | Exemplary |
|---|---|---|---|---|
| **Accuracy of calculations** | Calculations contain multiple errors. Sums or differences are incorrect. | Some calculations are correct; others contain errors. Shows inconsistent accuracy. | Calculations are accurate. Sums and differences are correct within 100. | Calculations are accurate and verified using inverse operations. |
| **Use of strategies** | No clear strategy shown. Work is unclear or missing. | Uses one strategy inconsistently. Strategy may be partially applied or confusing. | Uses a clear strategy such as making tens or doubles. Strategy is applied correctly. | Uses multiple strategies flexibly. Explains why a strategy works. |
| **Labelling and representation** | Model or report has no labels or labels are missing. Representation is unclear. | Model or report has some labels. Representation is partially clear or incomplete. | Model or report is clearly labelled. Numbers and quantities are easy to identify. | Model or report is clearly labelled with all parts identified. Representation shows understanding of composition. |
| **Problem solving** | Does not solve the problem or solution is incorrect. | Attempts to solve but solution is incomplete or partially correct. | Solves the problem correctly using addition or subtraction. | Solves the problem and shows how the same sum can be made in more than one way. |

## Scoring

Assign point values to each level: Beginning = 1 point, Developing = 2 points, Proficient = 3 points, Exemplary = 4 points. Add the points achieved across all four criteria. Use the following bands to determine the overall level: 4–6 = Beginning, 7–10 = Developing, 11–14 = Proficient, 15–16 = Exemplary.

## Notes for the Teacher

- Look for evidence that the student can work with numbers up to 100, not just within the teens. Accept any correct strategy, whether it uses tens, doubles, or counting on.
- When a student verifies using inverse operations (for example, checking 25 + 15 = 40 by calculating 40 − 15 = 25), mark the Accuracy criterion at Exemplary even if the initial calculation took longer.
- Accept models in any form: drawings, base-ten blocks, number lines, or written equations. A sum can be composed in multiple ways.
- For the Problem Solving criterion, "more than one way" means the student shows 35 = 30 + 5 and 35 = 20 + 15, for example. This aligns to the understanding that a sum can be composed in multiple ways ([Understanding](https://goa-cc-uat-aili-app-001.azurewebsites.net/explore/node/29847)).

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*AILI marking guide · language en · model claude-haiku-4-5-20251001 · generated 2026-09-17 · id 31d052b3-ab51-477f-884e-27da5bfaf10b*

### 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)