A Swansea University Science for Schools Scheme (S4) lesson plan and hands-on experimental workshop.

All S4 workshops follow the same format. They contain background information, a kit list, an experimental design, key words and concepts and learning outcomes and signposts for fur-ther information. You can also email any questions or queries to s4science@swansea.ac.uk

Slime and Spikes: a workshop on solids, liquids and gases.

2. Learning outcomes• Students will understand and be able to

explain the key differences between solids, liquids and gases

• Students will understand and be able to identify whether everyday items are solids, liquids or gases

• Students will be able to describe an example of a non-Newtonian fluid which behaves as both a liquid and a solid dependent upon how much force is applied to it.

3. Topics covered• Similarities and differences between solids,

liquids and gases including density differenc-es and differences in the speed of molecule movement.

• The differences in arrangements, motion and closeness of particles in solids, liquids and gases.

• The concept of changing state between solids, liquids and gases

• The anomaly of the ice-water transition• How changes in temperature cause a change

in the motion and spacing of particles.

1. What is the workshop about?Solids, liquids and gases, as the three most com-mon states of matter, are a keystone scientific concept. This workshop introduces the concept of states of matter as it relates to everyday materials, their properties and how those properties make different materials suitable for different tasks. Students are given an insight into why solids keep their shape, why liquids flow and why gases are used in place of liquids for uses such as keeping tyres inflated.

The workshop begins with an introduction to the three states of matter and how they are different. A worksheet is provided exploring the state of matter of everyday items.

There are then experiments exploring materials. The experiments introduce and allow a discussion of materials which can assume more than one state of matter (non-Newtonian fluids which act as either a solid or a liquid depending on how much force is applied) and magnetic fluids which change their properties when they are near a magnet. The experimental component has two parts; first a ‘slime’ is made, using PVA glue, bicar-bonate of soda and laundry detergent. The ‘slime’ behaves as a non-Newtonian fluid; if a strong force is applied it behaves like a solid (it will snap if pulled quickly) but it behaves like a liquid if a gentle force is applied (it will stretch a long way if pulled gently). The non-Newtonian ‘slime’ allows a discussion of particle movement as it relates to liquids and solids.

Summary: the lesson/workshop plan has two parts:

• A) Introduction – states of matter: the three common states of matter, solids liquids and gases

• B) The Experiments – ‘Slime’ workshop experiment: mixed states of matter, non-Newtonian fluids and magnetic liquids.

Part A can take up to 30 minutes. Part B can take up to 40 minutes.

Slime and Spikes: A workshop on states of matter (solids, liquids and gases) Physics workshop

Keywords and definitions

1. States of matter – The different forms that materials can take (e.g. solid, liquid or gas). The different forms can have different properties because their parti-cles are arranged differently.

2. Molecules and particles – The very small pieces of matter that everything is made from.

3. Non-Newtonian fluid – A material that changes how it flows and how run-ny it is when you apply a force to it (e.g. when you hit it or pull it). These aren’t liquids or solids, but something in-be-tween.

4. ‘Slime’ – A stretchy, rubbery material that feels like a soft solid when you play with it. When it is not being handled, it flows like a liquid, but it moves very slowly. It is a material in-between a solid and a liquid and will become more solid when a force is applied to it.

5. Magnetic fluid – A material that acts like a liquid, but that becomes a solid when it is near a magnet. When it is in a magnetic field, the runny liquid will start to grow spikes as it takes the same shape as the magnetic field. The magnetic fluid then has a definite shape, so it has be-come a solid.

4. Materials needed for the lesson/ workshop Consumables:

• PVA glue• Laundry detergent liquid containing Borax

(Formil, bio: this can only be purchased from Lidl (Aug 2017), contact lens solution can also be used instead).

• Poster paint or Food colouring (if you are using a new colour/brand, you should make a test batch of slime to check that the food colouring doesn’t stain your hands).

• Bicarbonate of Soda.• small plastic dishes or petri dishes.• Bags to keep slime in if it is to be taken

away. We would encourage the use of bio-degradable materials.

• Lollipop sticks.• Extra virgin olive oil.• Iron filings – these can be easily purchased

online.• Weak bar magnets e.g.

http://www.first4magnets.com/rectangular-bar-magnets-c38/16-x-4-x-50mm-long-fer-rite-bar-magnet-with-north-south-identi-fied-p8849

• Wet wipes.• Paper towels.• Bin bags.• Non-latex gloves – whilst the materials are

entirely safe, pupils may wish to wear gloves to keep their hands clean. If gloves are not worn pupils should wash their hands after handling the slime. Students with skin sen-sitivities should not handle slime containing washing detergent.

Re-usable items • plastic mixing bowls• plastic spoons/spatulas• Plastic tablecloth• Silly putty (a.k.a. ‘science putty’)• Rubber hammers• Magnetic putty (optional)• Strong magnet (optional)

5. Preparation Making the slime can take some practice. Try making a few batches before the workshop. It is also helpful to have a batch ready-made before the workshop so that you can show the student(s) what it should look like before they start .

Slime and Spikes: A workshop on states of matter (solids, liquids and gases) Physics workshop

B) The experiment B1 Testing the properties of silly putty:

1. Show the students the silly putty in the container. It has taken the shape of the con-tainer like a liquid. Take it out of the contain-er and show that you can hold and handle it like a solid.

2. Roll the silly putty into a ball and ask one of the students to flatten it against a table with their hands. This should be easy for them to do.

3. Ask another student to try to flatten it with the hammer. Ask them if they think it will be easy or difficult. You can give each student one attempt at flattening the putty with a hammer. If the students hit the putty sharply, it should retain its shape and may bounce, so it becomes difficult to flatten. If you hit it hard enough, the putty will even shatter, but you would need a much harder hammer for this.

4. Explain that the putty is a special type of solid (crystalline) and the more you push it, the more it pushes back and it becomes more solid when you hit it hard, so it won’t flatten. Show them that the putty will flatten when you press down on it gently with the hammer.

5. Get a student to pinch the putty and pull on it slowly; the putty should stretch into a long string. Get them to do the same, but pulling fast this time; it should snap as the greater force has made it more solid.

What is happening?Newton’s law of viscosity tells us that a liquid will retain its viscosity (its thickness) regardless of how much force we apply to it. This law isn’t true of all liquids though, when we make a liquid that acts ‘thicker’ or ‘thinner’ according to how much force we apply to it, we have made a ‘non-Newtonian liquid’.

When we apply a lot of force very suddenly to a non-Newtonian fluid, the particles cannot move fast enough to get out of the way and so the liq-uid becomes a solid.

More info here: http://www.chymist.com/Silly%20putty.pdfhttps://www.youtube.com/watch?v=Ye1VkBgl_W8https://www.sciencelearn.org.nz/re-sources/1502-non-newtonian-fluids https://www.sciencealert.com/physicists-might-have-just-solved-the-mystery-of-non-newtonian-fluids

6. Plan

A) Introduction

We suggest making up some introductory slides/worksheets from the information below.

A material’s state of matter refers to whether it is a solid, liquid or gas (there are actually a lot more than these three states of mater; non-Newtonian fluids, plasmas and glasses are all examples of materials that sit half way between two states of matter).

Solids have a definite shape and do not take the shape of their container. Examples of sol-ids: rocks, ice, trees, people.

Liquids do not have a definite shape and will take the shape of their container. Liquids flow (move) because of gravity and if there was no gravity, they wouldn’t flow. Examples of liq-uids: water, milk, lava, juice.

Gases do not have a definite shape. They sometimes take the shape of their contain-er and sometimes fly out of the top of their container depending upon whether they are heavier or lighter than air. Examples of gases: air, oxygen, carbon dioxide, steam.

The silly putty looks and acts like a solid when you hold it, but if you leave it for a long time in its tub, it will take the shape of its container and if you leave it on the table it will slowly form into a pud-dle, so it acts like a liquid (but a very slow-moving liquid). It is therefore somewhere between the two states.

We can sometimes change a material’s state of matter by changing its temperature. When you heat up water (liquid), it becomes steam (gas) and when you cool it down it becomes ice (sol-id). There are other ways of changing a material’s state of matter. With crystalline solids (like the silly putty and our slime), they become more solid when you apply a force to them which we will explore in the experiment.

Ferrofluids (magnetic liquids), change from liquids to solids when you apply a magnetic field to them (which we will look at in the experiment).

Slime and Spikes: A workshop on states of matter (solids, liquids and gases) Physics workshop

B3 Making slime1. Divide the students into groups. 2. This can get messy, so get the students to

roll up their sleeves and you can use a plastic tablecloth in case of any spills.

3. For each group, pour a small amount of PVA into a plastic mixing bowl so that the bot-tom of the mixing bowl is coated. Add a small amount of Bi Carb (no more than half a spoon) and mix it in.

4. Add a dash of the laundry detergent to each mixing bowl (there should be about 2 parts glue to one part laundry gel).

5. Add a few drops of either paint or food colouring to each bowl.

6. Each group should use a spoon/spatula to stir the mixture. As soon as they start to stir, there will be a chemical reaction and the liquid will turn much more solid. It will start out the consistency of porridge and will be difficult to stir, so the students in each group should take it in turns to stir the mixture until it is completely combined.

7. Check the consistency of each mixture, if it sticks to your hands you should add more laundry liquid, if it does not bind, add more glue.

8. Get the students to pick up the mixture out of the bowl and take it in turns to knead it with their hands. The best technique is for them to hold it in one hand, squeeze it as hard as they can, transfer it to the other hand, squeeze it, . . .

9. The goo is ready when it is completely mixed, stretchy and not sticky.

10. Students can explore how the slime behaves by stretching it quickly, it will break and then by stretching it slowly and seeing how far it will stretch. This behaviour shows a non-Newtonian fluid in action – if a lot of force is applied the slime breaks, like a solid, however if a small amount of force is applied the slime acts like a liquid and stretched.

11. Divide the goo up between the students in each group and give each student a plastic bag to take their goo away in.

More info herehttp://www.instructables.com/id/Three-Ways-to-Make-DIY-Silly-Putty/Watch a video of the slime being made here:https://www.youtube.com/watch?feature=youtu.be&v=gEBhbmFbTUo&app=desktop

B2 Making a magnetic fluid (ferrofluid): 1. Divide the students into groups. 2. Give each student (or pair) a petri dish.3. For each group, pour a small amount of olive

oil (~2-3 mm deep) into a plastic cup. Pour an equal amount of the iron filings into a separate cup.

4. Get one of the students to pour the iron filings into the olive oil. Then ask another stu-dent to stir the mixture using a lollipop stick until there are no lumps. The mixture should be a thick, black liquid with a mud-like con-sistency. If the mixture is too thick add more olive oil. You now have your ferrofluid.

5. Use the lollipop stick to put a drop of the ferrofluid onto each of the petri dishes and put the lids back on them.

6. Show that the ferrofluid takes the shape of the cup and can be poured, so it is a liquid.

7. Hand out the magnets and tell the students to hold them against the bottom of the petri dishes under the drop of ferrofluid.

8. The ferrofluid should become solid and ‘spikey’ as its shape it determined by the magnetic field lines coming out of the top of the magnet.

9. Get them to experiment by seeing what happens when they move the magnet around.

10. Don’t let them open the petri dishes or touch the ferrofluid. It is not dangerous, but it is really messy.

More info herehttp://www.instructables.com/id/ferromagnet-ic-fluid/

Slime and Spikes: A workshop on states of matter (solids, liquids and gases) Physics workshop