Science festivals

Non-Newtonian fluids, acid reactions to produce carbon dioxide, and understanding the reaction times of the human eye. All of these concepts are waiting to be explored.

Skill development

Learners will develop their working scientifically skills by:

• Selecting and planning the most appropriate ways to answer science questions, recognising and controlling variables where necessary, including:
  • Carrying out comparative tests.
  • Finding things out using a wide range of secondary sources of information.
• Drawing conclusions and raising further questions that could be investigated, based on their data and observations.
• Using appropriate scientific language and ideas to explain, evaluate and communicate their methods and findings.
• Asking their own questions about scientific phenomena.

Learning objectives

• Observe how magnets attract some materials and not others.
• Compare and group together everyday materials on the basis of their properties, including response to magnets.
• Explain that some changes result in the formation of new materials, and that this kind of change is not usually reversible, including changes associated with the action of acid on bicarbonate of soda.

Concepts supported

Children will learn:

• That some metals are magnetic – but not all materials are.
• That magnets have many real-life applications.
• That when acids and alkalis react new products are formed, and this type of reaction is irreversible:
  • That the products produced during these reactions can be of different states.

Extracting iron from breakfast cereal

Equipment

• Breakfast cereal containing iron
• Water
• Mortar and pestle
• Beaker
• Strong magnet

Procedure

1. Place a few flakes of cereal on a table or bench surface.
2. Hold the magnet close to the flakes and see if they stick to the magnet or are moved by it.
3. Reduce the size of some dry flakes by crushing them to a fine powder using a pestle and mortar. Spread the resulting powder on a piece of paper.
4. Place a magnet under the paper and move the paper over the magnet. Observe any effect the magnet may be having on the movement of the powder.
5. Do NOT put the magnet in direct contact with or close to the powder without the paper in between.
6. With careful manoeuvring, it should be possible to separate out fine grey specks of iron from the rest of the powder.

What’s the chemistry?

Many breakfast cereals are fortified with iron particles as a mineral supplement. As iron is magnetic, the particles can be separated from the cereal itself. 

Erupting volcano

Equipment

• Plastic drinks bottle
• Washing up liquid
• Food colouring
• Vinegar
• 2 tbsp bicarbonate of soda

Procedure

1. Stand the drinks bottle in a baking pan.
2. Fill the bottle most of the way full of warm water and a bit of red food colouring.
3. Add 6 drops of washing up liquid to the bottle contents. The washing up liquid helps trap the bubbles produced by the reaction so you get better lava. 
4. Add 2 tbsp bicarbonate of soda to the liquid.
5. Slowly pour vinegar into the bottle.
6. Eruption

What’s the chemistry?

The cold red lava is the result of a chemical reaction between the bicarbonate of soda and vinegar. Carbon dioxide gas is produced, which is also present in real volcanoes.  As the carbon dioxide gas is produced, pressure builds up inside the plastic bottle, until the gas bubbles erupt out of the ‘volcano’

Reaction times

Equipment

• A pencil
• A 30 cm ruler

Procedure

1. One person holds the ruler near the 30 cm mark and lets it hang vertically.
2. The other person places their thumb and index finger either side of the 0 cm mark, ready to catch it when it falls - their fingers shouldn’t touch the ruler.
3. Without warning, the person holding the ruler lets go, and the subject tries to catch the ruler as soon as possible.
4. The level (in cm) just above the subject’s first finger where the ruler was caught is recorded.

Hint: To prevent guessing, vary the time before letting go of the ruler.

What’s the chemistry?

This experiment tests how long it takes the brain to translate visual information into your voluntary (or conscious) motor commands and finally to initiate a response (grasping finger movements) that leads to the ruler being caught. The shorter the time between these events, the faster your reaction time.

Racing raisins

Equipment

1. A tall glass
2. Fizzy water (we found lemonade worked well)
3. Dry food (raisins, pasta, peas)
4. A timer or stopwatch

Procedure

Drop a raisin into the glass filled with fizzy water.

1. Why does the raisin sink?
2. How long does the raisin take to rise back to the top ?
3. Can you race two raisins?
4. What happens if you try other dried food?

What’s the chemistry?

Raisins are denser than the fizzy water, so will start to sink to the bottom. Bubbles of carbon dioxide stick to the rough surface of the raisin and when enough bubbles are attached, the raisin rises to the surface. At the surface, the bubbles burst, and the carbon dioxide escapes to the air. But now the raisin is heavier than the water again and will sink. The raisin will continue to rise and sink until most of the carbon dioxide has escaped.

Cornflour goop

Equipment

• Cornflour
• Water
• Mixing bowl
• Food colouring (optional)

Procedure

1. Add your cornflour to the bowl and then add about half as much water.
2. Stir until mixed in.
3. Add a little more water or flour until you have a strange paste. The paste should be difficult to stir. 

• What happens when you tap it with your finger?
• Can you pour it?
• Can you roll it into a ball?

What’s the chemistry?

Cornstarch molecules are big and act like a crowd of people: they move slowly round each other in water. If the movement is too fast, the big starch molecules bunch together giving the solution ‘solid’ properties.

Suggested activity use

These activities could be used as a carousel of activities to assess and check knowledge of previously taught topics, either during a science week or a science afternoon.

Alternatively, individual activities could be used within the appropriate topics being taught, as a way of carrying out fair tests, or for stimulating discussions. The activities are suitable for a whole class or as small group work with adult supervision.

Practical considerations

A strong magnet will be required to extract the iron from the breakfast cereal – normal horseshoe magnets may not be strong enough.

The making of the cornflour ‘gloop’ can be extremely messy, so you may want to take precautions to minimise mess.

Health and safety considerations will need to be taken into account with some of these activities – particularly when using vinegar and bicarbonate of soda.