Investigating: Stretchy Tights

In this worksheet, students will be taken on a journey through a whole investigation testing the elasticity of tights.

Key stage:  KS 2

Curriculum topic:   Working Scientifically

Curriculum subtopic:   Recording Data and Results

Difficulty level:

QUESTION 1 of 10

Mrs. Bates has collected lots of pairs of tights for her science class to test. She is going to help them to find out how stretchy tights are - they are made of an elastic material which is designed to stretch a certain amount.

Let's see how the investigation goes.

There are lots of different sorts of tights you can buy.

Which of the following differences do you think could affect how stretchy they are?

how much they cost

how long they are

what colour they are

how thick the material is

Mrs. Bates explains that they are going to add different objects to the tights to make them stretch.

What sort of object might be best?

some 100g masses

tins of baked beans

stones collected from the beach

Next, Mrs. Bates asks her class how they will measure how far the tights have stretched.

• Paul suggested using a metre ruler.
• Shannon suggested using a mass balance.
• Katy suggested using a tape measure.

Who do you agree with most?

Paul

Shannon

Katy

Mrs. Bates now gives each group a pair of tights, a set of masses and something to measure how far the tights have stretched.

Oliver wrote down on little pieces of paper his group's method of carrying out the investigation. Then his friend Harry brushed them all on to the floor by mistake.

Can you get them back into the correct order?

Column B

1
2
Measure the tights again.
3
Write down how much they've stretched.
4
First measure the length of the tights.
5
Keep measuring and adding weights until all the ma...
6

Now the class has finished all their measurements, Mrs. Bates is entering them on to a big chart on the board. She helps them draw a bar chart of their results. It looked like this.

Which group had the most stretchy tights?

6

5

4

3

2

1

Here's that bar chart again:

Look at the graph and decide which group's tights stretched the least far.

6

5

4

3

2

1

Having sorted out how much each group's tights stretched in total, Mrs. Bates has drawn another graph - this one shows how Group 1's measurements changed as they added their weights.

It looks like this.

Try to use the graph to decide whether the tights did most of their stretching at the beginning of the investigation, in the middle or at the end of the test.

end

middle

beginning

Why do you think it is important that tights are made out of an elastic material?

so that they're waterproof

so they fit comfortably

so they last a long time

• Question 1

There are lots of different sorts of tights you can buy.

Which of the following differences do you think could affect how stretchy they are?

how long they are
how thick the material is
EDDIE SAYS
If you're going to test how stretchy something is, its colour and cost don't really matter. What it's made of, as well as how long and thick it is, will make a difference to how it behaves when you start adding loads to it to see how far it stretches.
• Question 2

Mrs. Bates explains that they are going to add different objects to the tights to make them stretch.

What sort of object might be best?

some 100g masses
EDDIE SAYS
The nice thing about the 100g masses is that you know how heavy each one is: 100g. Also they're quite easy to attach to the tights to make them stretch. Cans of beans aren't bad, as they'll all be around 400g, but that's not very accurate and it's a bit of a big amount to add each time; also they're going to be tough to attach to the tights. Stones will be all sorts of weights, so that's not accurate at all.
• Question 3

Next, Mrs. Bates asks her class how they will measure how far the tights have stretched.

• Paul suggested using a metre ruler.
• Shannon suggested using a mass balance.
• Katy suggested using a tape measure.

Who do you agree with most?

Katy
EDDIE SAYS
They need to measure the LENGTH of the tights so Shannon is wrong as you cannot measure distance with a mass balance! Paul's metre rulers would work but they're awkward to handle, so Katy's tape measure idea is best.
• Question 4

Mrs. Bates now gives each group a pair of tights, a set of masses and something to measure how far the tights have stretched.

Oliver wrote down on little pieces of paper his group's method of carrying out the investigation. Then his friend Harry brushed them all on to the floor by mistake.

Can you get them back into the correct order?

Column B

1
First measure the length of the t...
2
3
Measure the tights again.
4
Write down how much they've stret...
5
6
EDDIE SAYS
When carrying out an investigation, it's tempting to dive straight in, but you'll soon come up against a problem you hadn't considered and you're likely to get lost. Oliver did the right thing in planning out how the experiment would go: measure/pull/measure/calculate/pull/measure/etc.
That way you'll end up with some useful results.
• Question 5

Now the class has finished all their measurements, Mrs. Bates is entering them on to a big chart on the board. She helps them draw a bar chart of their results. It looked like this.

Which group had the most stretchy tights?

4
EDDIE SAYS
Looking at the graph, the highest bar is Group 4's: theirs were the only tights to stretch over 30cm.
• Question 6

Here's that bar chart again:

Look at the graph and decide which group's tights stretched the least far.

5
EDDIE SAYS
The shortest bar belongs to Group 5: their tights stretched only 15cm, less than any other group's.
• Question 7

Having sorted out how much each group's tights stretched in total, Mrs. Bates has drawn another graph - this one shows how Group 1's measurements changed as they added their weights.

It looks like this.

Try to use the graph to decide whether the tights did most of their stretching at the beginning of the investigation, in the middle or at the end of the test.

middle
EDDIE SAYS
If you look at the shape of the line it goes up gently to start off - that means each mass is only stretching the tights a little. Then the line gets steeper - now each mass is making the tights stretch more than before. Finally, towards the end the line flattens out - the tights are nearly totally stretched, so they only stretch a little with each mass.
• Question 8

Why do you think it is important that tights are made out of an elastic material?

so they fit comfortably
EDDIE SAYS
Tights need to be stretchy so that they fit over legs comfortably, stretching to fit all the contours neatly. Hopefully they'll last a long time too, but they tend not to!
---- OR ----

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