# Measuring Accurately

In this worksheet, students study a variety of scientific equipment and how to use each piece accurately, as well as handling experimental data.

Key stage:  KS 4

Curriculum topic:  Working Scientifically: Vocabulary, Units, Symbols and Nomenclature

Curriculum subtopic:  Using Scientific Vocabulary and Nomenclature

Difficulty level:

### QUESTION 1 of 10

If you are shooting an arrow at a target, is it better to be accurate or precise? Surly as an archer, you want to be accurate, right? You want to hit that bulls’ eye – hit it right in the eye! But some people would rather you hit the same place each time at least that way they can trust you. Well, science has the same issues (only with equipment, not deadly arrows). Do you go for equipment that will tell you the correct results or do you go for equipment that will give you a small grouping of answers? This is what we will be looking at in this worksheet.

There is a variety of scientific equipment and apparatus for each scientific experiment. One needs to use them properly so the measurements taken are accurate. You will be presented with a variety of situations related to using scientific apparatus and handling data.

It is essential that scientific data are both accurate and precise:

• Accuracy is how close to the true value of a quantity the measurement is.
• Precision is the degree to which the results recorded will be the same if the experiment is to be reproduced under the exact same condition

A group of pupils perform an experiment twice under the same conditions. Their results are slightly higher the second time.

Is this statement true or false?

The experiment is not very precise.

true

false

Complete this sentence.

A pupil has measured the volume of water in a measuring cylinder to be 10 ml. The volume is actually 11 ml. The pupil's results are not very __________.

accurate

precise

repeatable

A pupil has made a miniature parachute and tests it to see how long it will take it to reach the ground.

He repeats the experiment five times and the measurements are as follows:

 1 20 s 2 20.1 s 3 21 s 4 20.5 s 5 19.9 s

There is variation in his measurements. What is the range of his measurements?

Clue: in order to find the range, you need to identify the lowest and highest measurement. It will also help to put the readings in order from low to high.

19.9 to 20 s

20 to 21 s

19.9 to 21 s

Have another look at the results.

 1 20 s 2 20.1 s 3 21 s 4 20.5 s 5 19.9 s

Now calculate the mean (average) of the readings.

Clue: in order to calculate the mean, you need to add all readings and then divide by how many there are.

23 s

20.3 s

101.5 s

A pupil needs to measure temperature in a water bath. She has two thermometers to choose from: a toy thermometer and a scientific laboratory thermometer.

Which one will be more accurate?

the toy thermometer

the scientific thermometer

A pupil has to compare the distances two toy cars travel on a ramp. He has two rulers: one with a millimetre scale and one with centimetres only.

Which one do you suggest he uses?

millimetre

centimetre

The meniscus is formed because different liquids react differently to surface tension. The diagram below shows the meniscus formed by water and mercury.

How do you correctly measure the volume of the liquid?

The highest point of the meniscus must be taken into account.

The lowest point of the meniscus must be taken into account.

The meniscus must be measured at eye level of the centre of the meniscus.

A pupil wants to measure the rate of photosynthesis in pond water in a large beaker of water. It can only be done by seeing the bubbles of oxygen and counting them. She wonders what she could do in order to increase the accuracy of her counting.

Choose the most appropriate solution.

She can't do the experiment accurately unless she finds a special instrument that can count the bubbles for her.

She can ask some of her classmates to count with her. The more people counting, the more chances are that they will count the correct number.

This is impossible and this experiment should not be done.

What does reliable data mean?

accurate data

reproducible results

valid results

A pupil is asked to measure the rate of reaction of hydrochloric acid and magnesium. She investigates the rate of reaction between sulfuric acid and calcium carbonate.

Why are her results not valid even though they are very accurate?

The results are precise, so they are valid.

The results are accurate, but not relevant.

The results can be reproduced easily.

• Question 1

A group of pupils perform an experiment twice under the same conditions. Their results are slightly higher the second time.

Is this statement true or false?

The experiment is not very precise.

true
EDDIE SAYS
The statement is true. For increased precision, the results should be the same. However, it is possible that measurements were not accurate and that has also affected precision.
• Question 2

Complete this sentence.

A pupil has measured the volume of water in a measuring cylinder to be 10 ml. The volume is actually 11 ml. The pupil's results are not very __________.

accurate
EDDIE SAYS
The pupil's results are not very accurate, because the measurement is 1 ml lower than the actual quantity.
• Question 3

A pupil has made a miniature parachute and tests it to see how long it will take it to reach the ground.

He repeats the experiment five times and the measurements are as follows:

 1 20 s 2 20.1 s 3 21 s 4 20.5 s 5 19.9 s

There is variation in his measurements. What is the range of his measurements?

Clue: in order to find the range, you need to identify the lowest and highest measurement. It will also help to put the readings in order from low to high.

19.9 to 21 s
EDDIE SAYS
Range = lowest to highest measurement, This means that the range here is 19.9 s to 21 s.
• Question 4

Have another look at the results.

 1 20 s 2 20.1 s 3 21 s 4 20.5 s 5 19.9 s

Now calculate the mean (average) of the readings.

Clue: in order to calculate the mean, you need to add all readings and then divide by how many there are.

20.3 s
EDDIE SAYS
The mean is worked out by: Adding together all of the values. Press = on the calculator AND THEN divide it by the number of items you added together. Mean = (20 + 20.1 + 21 + 20.5 + 19.9) / 5 = 20.3 s
• Question 5

A pupil needs to measure temperature in a water bath. She has two thermometers to choose from: a toy thermometer and a scientific laboratory thermometer.

Which one will be more accurate?

the scientific thermometer
EDDIE SAYS
The pupil will have more accurate results if she uses the scientific thermometer. More expensive equipment is more sensitive, and thus more accurate, as it can detect small changes in e.g. temperature.
• Question 6

A pupil has to compare the distances two toy cars travel on a ramp. He has two rulers: one with a millimetre scale and one with centimetres only.

Which one do you suggest he uses?

millimetre
EDDIE SAYS
The ruler with a millimetre scale will give a more precise measurement, as it can measure up to the closest millimetre.
• Question 7

The meniscus is formed because different liquids react differently to surface tension. The diagram below shows the meniscus formed by water and mercury.

How do you correctly measure the volume of the liquid?

The meniscus must be measured at eye level of the centre of the meniscus.
EDDIE SAYS
The meniscus must be measured at eye level of the centre of the meniscus, as shown in the image:

• Question 8

A pupil wants to measure the rate of photosynthesis in pond water in a large beaker of water. It can only be done by seeing the bubbles of oxygen and counting them. She wonders what she could do in order to increase the accuracy of her counting.

Choose the most appropriate solution.

She can ask some of her classmates to count with her. The more people counting, the more chances are that they will count the correct number.
EDDIE SAYS
She can ask some of her classmates to count with her. The more people counting, the more chances are that they will count the correct number. Sometimes more people working together can produce better results.
• Question 9

What does reliable data mean?

reproducible results
EDDIE SAYS
Reliable results are results that can be reproduced, if done under the same conditions, by you and others.
• Question 10

A pupil is asked to measure the rate of reaction of hydrochloric acid and magnesium. She investigates the rate of reaction between sulfuric acid and calcium carbonate.

Why are her results not valid even though they are very accurate?

The results are accurate, but not relevant.
EDDIE SAYS
The results are accurate, but not relevant. For results to be valid, they must be both reliable and relevant.
---- OR ----

Sign up for a £1 trial so you can track and measure your child's progress on this activity.

### What is EdPlace?

We're your National Curriculum aligned online education content provider helping each child succeed in English, maths and science from year 1 to GCSE. With an EdPlace account you’ll be able to track and measure progress, helping each child achieve their best. We build confidence and attainment by personalising each child’s learning at a level that suits them.