# Investigate: How Stretchy is a Spring?

In this worksheet, students will use the skills necessary to plan, carry out and report on an investigation into how stretchy springs from a Biro can be.

Key stage:  KS 2

Curriculum topic:   Exam-Style Questions: SATs Science

Curriculum subtopic:   Exam-Style Questions: Investigating

Difficulty level:

### QUESTION 1 of 10

As you'll hopefully have worked out by now, your EdPlace team are right here, helping you to nail your key science skills.

Science is all around us, part of everything we are and everything we do. We are naturally inquisitive beings, so investigations are actually part of everyday life and also the core of science.

Learning how to accurately plan, carry out, conclude and then report on an investigation is important.

The key is, to make sure your experiments are fun, not something that's tedious or boring.

So, journey along with your EdPlace chums, putting your learning into practice, and see what a difference it makes in your learning!

Now, Mrs. Bates has taken a bit of a risk with her science class. They wanted to find out how stretchy the spring in their school biros are. They can 'click' their biros hundreds of times, and they just seem to work without breaking.

"Mrs. Bates, can we get the spring out of the biro and test it to see how far it can stretch without breaking?" Katie wants to know.

Now their teacher can see springs and weights flying all over the room if they don't plan this right!

The class plan to unscrew their pens and take out the spring that makes it 'click' in and out.

Which variables must they control in their plan to make sure their test is fair?

Tick all the ones you agree with.

Make sure the pens are all the same colour

Make sure they're all the same model of pen

Make sure the pens are all the same length

Make sure they're all new pens, rather than used ones

What the class plan to do is to hang up the little springs so that they dangle above the desk. Then, the scientists will hang weights on them and measure how far the springs stretch.

Fill in the chart below to show which pieces of equipment they will need for this investigation.

 They'll need these They won't need these Ruler Thermometer Set of weights Spring Stopwatch Stand and clamp Paper and pencil Magnifying glass Weighing balance

Mrs. Bates has different sets of weights with individual masses on.

These will be added to each spring, one mass at a time.

Her different sets available are:

- 1 g masses

- 10 g masses

- 100 g masses

- 1 kg masses

Write in the box which set you think would be best for the class to use for stretching their pen springs (Just write the number, not g or masses).

Once the spring is hung up on the stand, with one of the weights dangling on it, the scientists have to decide what to measure.

Look at the diagram below.

Which of these do you think is the best to measure in order to find out how much the spring stretches?

A

B

C

Mrs. Bates sets the class off, adding masses and measuring their springs. Here is what Jordan has written in his group's results chart:

Number of Masses Length of Spring/cm
1 1.2
2 1.4
3 1.6
4 1.9
5 2.4

Jordan has made a major mistake!

Complete the sentence below to show what he should have done.

A

B

C

Once the class has completed the experiment, each group has a data record of how their spring behaved, written as a chart of numbers.

Mrs. Bates asks them to add a new column: "How much the spring stretched/cm".

She explains that they calculate this by working out how much longer the spring gets each time a mass was added.

Here is Alex's chart:

Number of Masses Added Length of Spring/cm Stretch of Spring/cm

1 1.0 0
2 1.2 0.2
3 1.6 0.2
4 1.9 0.3
5 2.4 0.5
6 2.8
7 3.0 0.2
8 3.0 0
9 3.0 0
10 3.0 0

Write in the box below the missing number from the stretch column:

Look at Alex's results for masses 7,8,9 and 10 - the length is the same!

Number of Masses Added Length of Spring/cm Stretch of Spring/cm

1 1.0 0
2 1.2 0.2
3 1.6 0.2
4 1.9 0.3
5 2.4 0.5
6 2.8
7 3.0 0.2
8 3.0 0
9 3.0 0
10 3.0 0

What do you think might have happened?

They measured it incorrectly

The spring has snapped

The spring has stretched as much as it can

Their rulers cannot measure past 3.0 cm

Let's assume that all of Mrs. Bates's groups have had similar results, that past about 7 or 8 masses, the spring just doesn't get any longer.

Predict what you expect each spring would do when the scientists remove all the masses from them.

It would 'ping' back to its original size

It would be a completely straight piece of wire

It would 'ping' back a bit, but be longer than it was at the start

It would have snapped in half

Mrs. Bates now shows the class how to convert their tables of results (their data) into a line graph. She says that this will help them to see what's been going on more easily.

Here's what Ashleigh's line graph looks like:

Look carefully at Ashleigh's graph and match up the section of the line (A/B/C) with how the spring is behaving.

## Column B

A
The spring stretches less and then stays the same ...
B
The spring is stretching a little more as each mas...
C
The spring is stretching the same amount as each m...

At the start of the investigation, the class agreed on this prediction:

"Biro springs are quite weak and will break once we add more than 5 weights to them."

On the basis of their experimental data, complete this sentence with one word:

## Column B

A
The spring stretches less and then stays the same ...
B
The spring is stretching a little more as each mas...
C
The spring is stretching the same amount as each m...
• Question 1

The class plan to unscrew their pens and take out the spring that makes it 'click' in and out.

Which variables must they control in their plan to make sure their test is fair?

Tick all the ones you agree with.

Make sure they're all the same model of pen
Make sure the pens are all the same length
Make sure they're all new pens, rather than used ones
EDDIE SAYS
In any investigation there are going to be a load of variables and one of your tasks, as a scientist, is to work out which ones you have to control so that your results make sense. So, if the pens were different colours, would that affect the behaviour of the springs inside? No, it wouldn't. What about how old the pen was? Definitely. What if some were longer than others - might they need a different spring? Quite possibly. Do you think they all need to be made by the same manufacturer and be the same model? Definitely! You see, you're looking for uniform springs, ones that should behave in a similar manner, so you can compare them accurately.
• Question 2

What the class plan to do is to hang up the little springs so that they dangle above the desk. Then, the scientists will hang weights on them and measure how far the springs stretch.

Fill in the chart below to show which pieces of equipment they will need for this investigation.

 They'll need these They won't need these Ruler Thermometer Set of weights Spring Stopwatch Stand and clamp Paper and pencil Magnifying glass Weighing balance
EDDIE SAYS
This needs thinking about - you've got to imagine you're one of the scientists about to stretch a spring and measure how far it stretches. So, you're going to need a ruler (to measure the length of the spring), weights to stretch it, a stand to hang it from, paper to write down your results - that sort of thing. Equipment like a thermometer or a weighing balance, won't help you to measure how far a spring stretches.
• Question 3

Mrs. Bates has different sets of weights with individual masses on.

These will be added to each spring, one mass at a time.

Her different sets available are:

- 1 g masses

- 10 g masses

- 100 g masses

- 1 kg masses

Write in the box which set you think would be best for the class to use for stretching their pen springs (Just write the number, not g or masses).

10
EDDIE SAYS
Little pen springs? Surely 100 g or 1 kg masses are way too big? Will 1 g stretch them at all? That's the weight of a £5 note! 10 g is probably best.
• Question 4

Once the spring is hung up on the stand, with one of the weights dangling on it, the scientists have to decide what to measure.

Look at the diagram below.

Which of these do you think is the best to measure in order to find out how much the spring stretches?

A
EDDIE SAYS
A is measuring the actual length of the spring, so that's the best one to choose. B is OK, but you're including the length of the mass and hanger, so whilst you'll find out how much it all stretches, you'll never know the actual length of the spring. C is the length of the stand, which we aren't measuring!
• Question 5

Mrs. Bates sets the class off, adding masses and measuring their springs. Here is what Jordan has written in his group's results chart:

Number of Masses Length of Spring/cm
1 1.2
2 1.4
3 1.6
4 1.9
5 2.4

Jordan has made a major mistake!

Complete the sentence below to show what he should have done.

EDDIE SAYS
In experiments like these it's vital to take a base reading - what the situation is at the start! So, here, that's the original length of the spring with nothing hanging on it. If they don't know the original length, how will they know how far the mass they've added has made it stretch?
• Question 6

Once the class has completed the experiment, each group has a data record of how their spring behaved, written as a chart of numbers.

Mrs. Bates asks them to add a new column: "How much the spring stretched/cm".

She explains that they calculate this by working out how much longer the spring gets each time a mass was added.

Here is Alex's chart:

Number of Masses Added Length of Spring/cm Stretch of Spring/cm

1 1.0 0
2 1.2 0.2
3 1.6 0.2
4 1.9 0.3
5 2.4 0.5
6 2.8
7 3.0 0.2
8 3.0 0
9 3.0 0
10 3.0 0

Write in the box below the missing number from the stretch column:

0.4
.4
EDDIE SAYS
Did that makes sense? Can you see that when Alex's group added the fifth mass, the spring's length changed from 1.9 cm to 2.4 cm? That's an increase (stretch) of 0.5 cm (2.4 - 1.9 = 0.5). So, when they add the sixth mass, and Alex forgets to fill in the chart, it doesn't matter as they've got the new length: 2.8 cm. That's a 0.4 cm stretch (2.8 - 2.4 = 0.4). Got it?
• Question 7

Look at Alex's results for masses 7,8,9 and 10 - the length is the same!

Number of Masses Added Length of Spring/cm Stretch of Spring/cm

1 1.0 0
2 1.2 0.2
3 1.6 0.2
4 1.9 0.3
5 2.4 0.5
6 2.8
7 3.0 0.2
8 3.0 0
9 3.0 0
10 3.0 0

What do you think might have happened?

The spring has stretched as much as it can
EDDIE SAYS
At first it all seems a bit weird - add more weight and the spring doesn't stretch any more. Has it snapped? No, because it would have got shorter! They could have measured it wrong, but probably not four times ... and a 3 cm ruler - pretty useless! No, it's just that the spring has stretched all it can - it probably looks like a straight-ish piece of wire now! It just can't stretch any more.
• Question 8

Let's assume that all of Mrs. Bates's groups have had similar results, that past about 7 or 8 masses, the spring just doesn't get any longer.

Predict what you expect each spring would do when the scientists remove all the masses from them.

It would 'ping' back a bit, but be longer than it was at the start
EDDIE SAYS
Remember, this is a prediction- you don't know the answer, but you're using data and experience to help you. The data tells you that the spring hasn't snapped - it's just stopped stretching. It's also not going to have turned into a completely straight piece of wire. Remove the weights that were stretching it and it will go back into a spring shape, but not the way it was at the start. The fact that the last four results stayed the same tell you that the spring has been 'over-stretched' - it's gone past its Elastic Limit.
• Question 9

Mrs. Bates now shows the class how to convert their tables of results (their data) into a line graph. She says that this will help them to see what's been going on more easily.

Here's what Ashleigh's line graph looks like:

Look carefully at Ashleigh's graph and match up the section of the line (A/B/C) with how the spring is behaving.

## Column B

A
The spring is stretching a little...
B
The spring is stretching the same...
C
The spring stretches less and the...
EDDIE SAYS
This is a little tougher! Let's take section B (in blue) first: can you see it's a straight line, angling upwards? That means that as each mass is added, the spring gets longer by the same amount each time - that means that it's stretching the same amount every time 10 g more is added. What about section A (in red): it's curving slowly upwards - that means its slowly getting longer as each mass is added. In other words, each 10 g mass stretches it a bit more. Now, in section C the line is curving less and then staying straight. Each 10 g mass hardly makes it stretch at all and then it stays the same length. It's stretched as much as it can. Does that make sense?
• Question 10

At the start of the investigation, the class agreed on this prediction:

"Biro springs are quite weak and will break once we add more than 5 weights to them."

On the basis of their experimental data, complete this sentence with one word:

EDDIE SAYS
That's the beauty of actually doing an investigation - finding out whether the item (a spring in this case) behaves as you think it will. It's not a case of being right or wrong - it's finding out what's actually going on and expanding your understanding of the world around you. Science is great!
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