Application of Number

Level 2

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Estimating Measures - Tutorial 1

We all need to be able to estimate measures accurately. Sometimes when we measure things, the scale does not give us an accurate enough measurement and so estimating is useful.

These short tutorials will give you experience of estimating some different scales, with a short interactive assessment at the end of each one.

The image opposite shows a weighing pulley. These are often used in Science or for scales at supermarkets, greengrocers, butchers, etc. Look at the scale. We can see that the main markings are measured in unit Kg, i.e 1Kg, 2Kg, 3Kg, etc. The smaller markers are half Kgs, i.e. 0.5Kg, 1.5Kg, 2.5Kg, etc. Measurement A is not actually on any marker and so we will need to estimate its reading. The smaller marker just below A is 0.5Kg. Look at the image below. You can see that A is just over half way between 0Kg and 0.5Kg. We can split the distance between 0 and 0.5Kg into 5 sections. Each one is 0.1Kg, i.e. 0.1, 0.2, 0.3, 0.4 and 0.5Kg. This looks like this. You can see that A is pointing to 0.3Kg.

Let us look at B.

This time it is between 1 and 1.5Kg. It is not quite half way. Split the space between 1 and 0.5Kg into 5 sections. What do you think B is?

Look at the animation below, which shows the 5 sections put in place.

You can see that B is 1.2Kg, because it is less than half way.

Look at C.

It is between 1.5 and 2Kg. It is slightly over half way. It is:

Look at D.

This is easy, because it is on the marker. It is 2.5Kg.

To practise estimating using this scale try this assessment.

Then go on to the next tutorial.

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