Testing Fairly
Aligned to 3-5-ETS1-3 — Next Generation Science Standards.
What this lesson teaches
To find out which design works best, engineers run a fair test. A fair test changes only one thing at a time and keeps everything else the same, so the results can be trusted. Watching where a design fails shows what to improve.
Worked example
To see which paper airplane flies farther, you throw both with the same force from the same spot, changing only the plane's shape — not how hard you throw.
Practice questions
- In a race between two toy cars, what should you keep the same to make the test fair?
- Plan a fair test to find out which cup keeps water warm the longest.
- Explain why changing only one thing at a time makes a test fair, and how a failure can help you improve a design.
Watch the lesson
Every lesson comes with a video taught in English and Spanish — the same video the QR code in the printed workbook opens.
▶ Watch this lessonEn español
Probar de manera justa
Para descubrir qué diseño funciona mejor, los ingenieros hacen una prueba justa. Una prueba justa cambia solo una cosa a la vez y mantiene todo lo demás igual, para que se pueda confiar en los resultados. Observar dónde falla un diseño muestra qué mejorar.
Ejemplo: Para ver cuál avión de papel vuela más lejos, lanzas los dos con la misma fuerza desde el mismo lugar, cambiando solo la forma del avión — no la fuerza con que lo lanzas.
More Engineering Design lessons
Teach this lesson today
An AI tutor that guides with questions instead of just giving answers — all K–12 core subjects, every child in the family.
Start free — no card required