Reach for the Star | GCSE Mathematics

L055: Rounding error intervals and bounds

Objective

Describe rounding intervals and reason about limits of accuracy.

Calculator: Calculator allowed where labelled; non-calculator reasoning remains required.

Visual model for Rounding error intervals and bounds
Points route: Connect 2 · Share 2 · Apply 6 · Review 3 · Stretch 2 · Deep Challenge 3. Record your score honestly after you have checked your answer.

Recall

Retrieve the key fact or method needed for rounding error intervals and bounds.

Core practice

A rectangle is 8.2 cm by 5.6 cm to the nearest 0.1 cm. Find its lower area bound.

Reasoning

A rounded length is 10 cm to nearest cm. Is 10.5 cm included? Explain.

Exam-style

Solve an exam-style problem involving rounding error intervals and bounds. Show working, include a check and interpret your answer.

WWW / EBI

Recall & Review: feedback and extension integration

Lesson L055: Rounding error intervals and bounds

Objective: Describe rounding intervals and reason about limits of accuracy.

60-minute structure: 0-7 Connect & Check; 7-14 Share; 14-25 Present/model; 25-44 Apply route choice/practice; 44-52 independent exam-style check; 52-60 Recall & Review, WWW/EBI and next step.

What Went Well (WWW)

I selected an efficient numerical method, showed the key steps clearly and checked the sign, size or accuracy of my answer.

Even Better If (EBI)

I will make the place-value, sign or operation decision explicit and use estimation or an inverse calculation to check a fresh question.

Stretch and deep challenge

Stretch: A rectangle is 8.2 cm by 5.6 cm to the nearest 0.1 cm. Find its lower area bound.

Deep challenge: A rounded length is 10 cm to nearest cm. Is 10.5 cm included? Explain.