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Day 17 · September 17, 2026

An app to practice rounding numbers with number lines

DAY 17 of building a free app for a teacher every single day!! Today, we build a number rounding practice app for Nancie’s third grades!

Check it out at lines.teacher.dev

The full app

Rounding with Number Lines

Guided rounding practice that helps students use number lines to find endpoints, midpoints, and nearest values.

See the app →