Myths about teaching can hold you back
- Year 8
Rounding errors
I can appreciate the impact of rounding errors when using a calculator (or other technology), and the way that these can be compounded to result in large inaccuracies.
- Year 8
Rounding errors
I can appreciate the impact of rounding errors when using a calculator (or other technology), and the way that these can be compounded to result in large inaccuracies.
Lesson details
Key learning points
- When given a rounded number you can say what the biggest and smallest values of the unrounded number could have been.
- When using technology for multi-step calculations you might round along the way.
- Rounding too early can cause answers to be incorrect
- Repeated rounding in multi-step calculations can lead to large errors.
Keywords
Significant figures - Significant figures are the digits in a number that contribute to the accuracy of the number
Common misconception
Rounding prematurely during multi-step calculations.
Encourage to use of fractions (where possible) or the use of the ANS button.
To help you plan your year 8 maths lesson on: Rounding errors, download all teaching resources for free and adapt to suit your pupils' needs...
To help you plan your year 8 maths lesson on: Rounding errors, download all teaching resources for free and adapt to suit your pupils' needs.
The starter quiz will activate and check your pupils' prior knowledge, with versions available both with and without answers in PDF format.
We use learning cycles to break down learning into key concepts or ideas linked to the learning outcome. Each learning cycle features explanations with checks for understanding and practice tasks with feedback. All of this is found in our slide decks, ready for you to download and edit. The practice tasks are also available as printable worksheets and some lessons have additional materials with extra material you might need for teaching the lesson.
The assessment exit quiz will test your pupils' understanding of the key learning points.
Our video is a tool for planning, showing how other teachers might teach the lesson, offering helpful tips, modelled explanations and inspiration for your own delivery in the classroom. Plus, you can set it as homework or revision for pupils and keep their learning on track by sharing an online pupil version of this lesson.
Explore more key stage 3 maths lessons from the Estimation and rounding unit, dive into the full secondary maths curriculum, or learn more about lesson planning.
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Lesson video
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Prior knowledge starter quiz
6 Questions
Q1.An __________ is any positive or negative whole number and zero.
Q2.Round 384 to the nearest 10.
Q3.Round 30.499999 to the nearest integer.
Q4.Round 0.0002832 to 1 significant figure.
Q5.When a number is rounded to the nearest integer it is 4. Select the possible unrounded numbers.
Q6.Round each number in the calculation to 1 significant figure and calculate the answer. $$\frac{89.7+9.58}{5.34+4.58}$$. Give your answer as an integer.
Assessment exit quiz
6 Questions
Q1.State the smallest and largest integers that round to 680 when rounded to the nearest 10.
Q2.State the smallest and largest integers that round to 500 when rounded to the nearest 20.
Q3.State the smallest and largest integers that round to 700 when rounded to the nearest 50.
Q4.An advert for a magazine says 37 000 people buy the magazine rounded to the nearest 1000. The fewest people who buy the magazine is people.
Q5.A plot of rectangular land measure 2.39 km (1 d.p.) by 5.78 km (1 d.p.). Five pupils work out the area of the plot of land. Whose working out and answer shows the most accurate answer to 1 d.p?
Q6.A large plot of land has an area of 20 km². A small, rectangular lake with lengths 3.254 km by 4.814 km is planned, leaving the rest of the land as grass. Work out the area of grass to 1 d.p.