---
title: "Choosing the right strategy"
description: "Choose the best tool for each task, such as mental maths, written working, a number line or a ruler, and explain why it fits."
canonical: https://lightmysky.com/learn/mathematics/choosing-the-right-strategy-mt_mQcWGh02no
source: https://lightmysky.com/learn/mathematics/choosing-the-right-strategy-mt_mQcWGh02no.md
retrieved: 2026-10-19
---

> **Agent view.** This is the Markdown twin of the page, for tools and assistants.
> When to use this site, and the call that answers each job: https://lightmysky.com/agent-instructions.md
> API description (OpenAPI 3.1): https://lightmysky.com/openapi.json · Authentication: https://lightmysky.com/auth.md
> Pricing: https://lightmysky.com/pricing.md · Catalog: https://lightmysky.com/llms.txt · Full catalog: https://lightmysky.com/llms-full.txt
> Every machine-readable file on this domain: https://lightmysky.com/.well-known/ai-catalog.json
> Ask for Markdown with `Accept: text/markdown`, a `.md` address, or `?mode=agent`.

# Choosing the right strategy

Choose the best tool for each task, such as mental maths, written working, a number line or a ruler, and explain why it fits.

Subject: Mathematics · Area: Mathematical Thinking · Ages 7 to 8
Page: https://lightmysky.com/learn/mathematics/choosing-the-right-strategy-mt_mQcWGh02no

## Ready when they can

- Choose a mental method for 345 + 200 but a written method for 345 + 278
- Select a ruler vs a metre stick based on the object being measured
- Decide when a number line is more useful than base-ten blocks for a given problem

## Lesson: Choosing the right strategy

Not every math problem needs the same tool. Before you start, take a second to look at the numbers and think about what will work best: your head, a pencil and paper, or a picture.

**Example.** Zara sees 250 + 300. She adds the 300 in her head: 250, 350, 450, 550, done. Then she sees 246 + 379. The numbers do not round evenly, so she writes it down and adds column by column so she does not lose track of the carrying.

*(drawing: For 47 + 8, hopping along a number line gets you to 55 fast: start at 47, then jump 8 more.)*

For measuring, grab a ruler for a pencil but a metre stick for a doorway. For adding, blocks help you see small groups, but hopping on a number line can be quicker for bigger jumps. Pick the tool that fits the size of the problem.

**Recap.** Look at the problem first, then choose the tool, mental math, paper, a number line, or the right measuring tool, that fits it best.

## Practice

17 questions on this page, each with its working shown.

## Needs first

- [Measuring length (age 7+)](https://lightmysky.com/learn/mathematics/measuring-length-age-7-mt_e4x3l2JeLI)
- [Adding and subtracting (age 7+)](https://lightmysky.com/learn/mathematics/adding-and-subtracting-age-7-mt_SrrsLiJkr3)
- [Choosing a tool or representation](https://lightmysky.com/learn/mathematics/choosing-a-tool-or-representation-mt_zMEvtigoM3)

## Opens up

- [Choosing mathematical tools](https://lightmysky.com/learn/mathematics/choosing-mathematical-tools-mt_d-WZC2OyMB)