Number Line: Solving Problems [TEKS Tools Grade 3]

This post specifically looks at how number lines can be used to solve a variety of problems involving rounding, estimation, and the four operations. Read more about TEKS Tools and their rationale here.

Solving Problems

Number lines, the second TEKS Tool, account for around 22% of each 3rd grade STAAR test. Within this tool are many uses: representing and comparing fractions, interpreting number pair relationships, and solving problems involving rounding and the operations.

The main function of a number line is to show the relationship between fractional quantities, number pairs, or as a tool for rounding and estimation. By visualizing these quantities on number lines, students can better make sense of the how the quantities are related.

Rounding/Estimation

Students first learn to round numbers by reasoning about a number's relative proximity to a benchmark number. Utilizing number lines increases conceptual understanding that builds to the rounding algorithm.

3.2C - represent a number on a number line as being between two consecutive multiples of 10; 100; 1,000; or 10,000 and use words to describe relative size of numbers in order to round whole numbers

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2024-8: students are given two benchmarks and asked to find a number that is more than halfway between them

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3.4B - round to the nearest 10 or 100 or use compatible numbers to estimate solutions to addition and subtraction problems

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2024-17: multiple quantities were given that needed to be rounded, students had to find the estimated total

2025-29: multiple quantities were given that needed to be rounded, students had to find the estimated total

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Addition/Subtraction

While strip diagrams are the primary tool for solving operational problems, students will transition to number lines in middle school. Some 3rd grade problems, including time intervals, lend themselves to number lines as the primary tool for understanding them.

3.5A - represent one- and two-step problems involving addition and subtraction of whole numbers to 1,000 using pictorial models, number lines, and equations

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2025-14: a real-world situation was shown on a number line, students had to interpret and explain it

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3.7C - determine the solutions to problems involving addition and subtraction of time intervals in minutes using pictorial models or tools such as a 15-minute event plus a 30-minute event equals 45 minutes

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2025-26: a real-world situation was given, students had find the starting time using an ending time and the time interval