MATHS - CLIL

ROUNDING UP AND DOWN

Course / Level: 2º Eso (compulsory secondary education)

Subject: Maths

Introduction

Sometimes exact answers to a problem are unnecessary or even impossible, and a sensible approximate answers is needed. In this unit, you will meet a variety of ways of approximating numbers. Then you will use approximate values to find estimates to calculations, to solve problems and see how approximation and measurement are related.

Learning Outcomes:

-  To round whole and decimal numbers to a specified decimal place.
- To find estimates in practical problems.
- To use rounding in real-life problems.
- To measure accuracy of measurements. 

Subject Content:

• Rounding up and rounding down decimal numbers to the nearest tenth, hundredth and thousandth.
• Rounding up and rounding down whole numbers to the nearest ten, hundred and thousand.
• Significant figures.
• Estimates.
• Accuracy of measurements. 

Methodology:

Use of ICT resources (videos, powerpoint) to introduce concepts and support explanations. Working in pairs on the worksheets given. Learning by doing and solving problems. Developing of key competences trying to work out solutions to every-day problems. 

Resources:

Videos:

https://www.youtube.com/watch?v=fd-E18EqSVk (Maths antics)

https://www.youtube.com/watch?v=eCJ76hz7jPM (Khan Academy)

https://www.youtube.com/watch?v=-UMk8y0Rfig (UK Maths teacher)

Worksheets:

http://www.mathworksheets4kids.com/rounding-decimals.php Link 1

http://www.mathworksheets4kids.com/estimate-fractions-decimals.php Link 2

http://www.mathworksheetsland.com/hsnumbersquan/6accru/lesson.pdf Link 3

Powerpoint:

http://es.slideshare.net/franc1md/rounding-powerpoint

Sessions:

Session 1: introduction to approximation: the need of an approximate answer for practical problems. Brainstorming at the beginning of the lesson about the need of approximation (all students). Video showing of rounding: Maths antics. Worksheet about rounding whole numbers to the nearest ten, hundred and thousand: mathsworksheets4kids. 

Session 2: briefing about rounding: showing powerpoint. Rounding whole numbers in real-life problems: activity 1 and 2 in pairs. Rounding in practical problems worksheet (examples a, b and c) (in pairs).

Session 3: rounding decimal numbers to the first/second/third decimal place: mathsworksheets4kids, link 1 (individual). Video showing about significant figures: khan academy. Worksheet for finding estimates for some calculations involving all operations: addition, subtraction, multiplication and division (groups of 3), link 2.

Session 4: all measurements are approximate. Brainstorming about accuracy of measurements. Video showing: uk maths teacher. Worksheet with practical problems about this topic (in groups of 4), link 3.

One more session may be added is needed to make sure all students reach the evaluation criteria about rounding. 

TASKS EXAMPLES: 

Word problems examples:

1.- The attendance at a Manchester United soccer match was 61267. Round this number to the nearest hundred.

2.- In a census, the population of Wolverhampton was given as 242187. Round this number

a) to the nearest thousand.

b) to the nearest hundred thousand.

Rounding in practical problems examples:

a) How many boxes, each holding 6 eggs, can be filled with 250 eggs? How many eggs are left over?

b) How many cars, each 4.5 m long, would fit end to end on a ferry deck which is 31 m long.

c) 190 tiles are needed for a bathroom. The tiles are sold in boxes of 20. How many boxes are needed?

Accuracy of measurements example:

The world record for the women’s 100 metres is 40.49 seconds.

a) To what degree of accuracy is this time given?

b) Write down the minimum and maximum time this could be.

c) What is the maximum possible error?