Locusts and Glowsticks

Public summary: 

What do glowsticks and locusts have in common? Watch what happens as we heat them up and cool them down - how long can you get your glowstick to glow? How fast can you make the locusts move?

Using glow sticks to talk about chemical kinetics.
Useful information
Kit List: 

- lamp (heat only if possible)
- 2 tanks of locusts
- glow sticks
- knife/ scissors to open glowstick packet
- ice cubes for cooling
- washing up bowl
-sometimes dry ice may be available for cooling. If dry ice is used, the Dry Ice Risk Assessment must be read and understood as well.

Packing Away: 

Bin any used glow sticks.
Return unused glow sticks to stores.
Dry ice can be left in well ventilated area to boil.

Frequency of use: 

Use cooling glow sticks in dry ice to stop the light-emitting reaction to show that reactions happen faster when they're warm.

Locusts (cold blooded) in warm and cool environments can be used to point out that this is true of the reactions of life too, but this is not essential.

*** OVERVIEW ***

Cooling glow sticks in ice to stop the light-emitting reaction to show that reactions happen faster when they're warm. Use locusts (cold blooded) in warm and cool environments to point out that this is true of the reactions of life too.

Possible activities:
- Demonstrating how cooling slows down reactions using glowsticks and ice/dry ice.
- Demonstrating how cooling slows down reactions using locusts and ice.

Other things to talk about:
- Other reactions which are affected by heat which we see in our everyday lives.

Tips for demonstrating:

- It is quite useful to be aware for this experiment how much difference the "Really Cool Show"/liquid nitrogen demonstration makes to how quickly children pick up the ideas you feed them, especially about temperature/ reactions and the fact that solid carbon dioxide takes up much less space than the gas.

- If using dry ice: be aware that a box of dry ice with a glowstick inside it will have a fascinating (at least to a small child) glow. It is very important to retain control of the experiment (I often achieve this by sitting on the lid of the polystyrene dry ice box) whilst giving your demonstration since if a small sibling loses interest in your talk (s)he may try to conduct an experiment of her/his own!


- Place tanks of locusts side by side, shine the lamp on the outer face of one of the tanks.

- Break and cool a couple of glowsticks in icy water as "ones I prepared earlier".

- Start with glowsticks- get a glowstick out. Remove end-cap and ribbon as they cause confusion (children think they're important).

- Have the children seen glowsticks before? When? Fireworks night? Parties?. If not, it may be best to snap the glowstick first and see what it does.

- Do they know how glowsticks work? The usual answer, if any, is "You bend them".Explain that what happens when you bend them is that the inner glass tube breaks and the two chemicals mix. (With the yellow glowsticks you can see the glass tube before breaking it

- Get one of the children to snap the glowstick and give it a shake now that it's glowing.

- How can we stop it? Suggestions usually include "bend it again", "unmix it", "open the tube". Deal with these ideas first - unmixing could be compared to mixing red and green paint to make brown then trying to unmix. Quite often a parent will prompt the child to say "put it in the freezer" in which case the next bit is explaining why, not drawing out what!

- A possible route to how to stop a reaction is through how we stop food from going off... work children round to "put it in the fridge".

- Explain that everything is made up of little bits moving around and banging into each other, and if things are hotter the little bits move faster and bang into each other harder.

- Describe reactions as bits banging into each other and knocking bits off/ getting new bits stuck on, possibly pointing out that you hurt yourself more if you fall off your bike/ fall over when running than if you trip up when walking.

- Get the icy water out and explain that it is colder than room temperature, more like your fridge at home. Put the glowsticks in the water and put it away again.
- If using dry ice, can talk about dry ice and what it is, maybe put a couple of pieces in a bowl of water and watch them bubble, talk about the gas expanding and taking up more space.

- Move on to locusts and ask the children to look at the locusts, and to decide which set are moving about more. In general they're pretty obliging and it will in fact be the "warm tank" locusts which move about more.

- Explain to children that the locusts, like them, get their energy to move about from reactions of their food. Tell them that their bodies have lots of systems to make sure they stay at the same temperature... they are warm-blooded (many will have heard the term before).

- Explain that locusts haven't got these systems (they are cold-blooded) so they can only get energy out of their food to move about if they're warm enough. Point out that this is like the glowsticks, which only give off light if they're warm enough.

- This all tends to be very counter intuitive to the less scientific parent, some have trouble with the idea that locusts don't just want to lie down if it's hot, like they do themselves!

- Get the icy water out again and show that the glowsticks are glowing much less. They probably won't have gone out yet (unless the group were particularly fascinated by the locusts!).

- How can we start the glowstick glowing again/much brighter?. Warm up the glowstick by removing it from the water/dry ice (carefully, it will be very cold!) and holding it.

- Explain that now the particles can bang into each other again as they have enough energy (are moving around fast enough).

- If children are still engaged, can talk about the magnetic molecular models.

- Give the glowstick to one of the children. Repeat 'til fade.


- Other reactions which are affected by heat which we see in our everyday lives.

- The differences between hot-blooded and cold-blooded animals.


- This experiment concerns reaction rates and their dependence on temperature.

Risk Assessment
Date risk assesment last checked: 
Wed, 17/01/2018
Risk assesment checked by: 
Date risk assesment double checked: 
Sun, 04/02/2018
Risk assesment double-checked by: 
Risk Assessment: 
DESCRIPTION Look at glow stick in darkened box then cool using ice/salt mix. Look at it again. Compare with activity of locusts in hot and cold conditions. Wooden "molecules" can be stuck and unstuck from each other (using magnets) to show the idea of a chemical reaction.
RISKS # 1. Glow stick contents are non-toxic, but contents potentially damaging to eyes. Glass ampoule inside the glowstick is broken to activate stick, but small chance of contents leaking
# 2. Salt ice mix is cold. Contact with it can hurt and prolonged contact could cause skin damage.
# 3. Salt solution is strongly ionic and therefore electrically conducting. Risk of electric shock in contact with lamp.
# 4. High ionic strength solution will hurt on contact with eyes.
# 5. The lamp warming the locusts can get hot - risk of burns
# 6. Reaction model contains rare earth magnets (strong - risk of them slamming together and smashing, or trapping skin)
# 7. Very small likelihood of repeated exposure to locusts causing the demonstrator to either have an asthma attack (if they already have asthma) or for them to develop an allergy to locusts. Even smaller risk of locusts setting off asthma attacks or allergic reactions in public.
ACTION TO BE TAKEN TO MINIMISE RISKS # 1. Take care not to break outer skin of glowstick. Demonstrator must know the location of the nearest eyewash. If giving glowsticks to children to take away, warn the parents/guardians that contents should not be allowed to come into contact with eyes and that glowsticks should not be put in the mouth or chewed. Ideally do not give glowsticks to children below the age of about eight years.
# 2. Do not allow anyone else to touch the ice water.
# 3. Ensure that all electrical appliances and plugs are above ground level and safe from spills of salt solution. Do not allow children to put their hands in the cold solution. Do not allow anyone else to touch the lamp, dry hands if you need to touch it.
# 4. Advise children not to touch their eyes, if they have touched the wet glow sticks, as the salt will sting.
# 5. Warn children not to touch lamp.
# 6. Demonstrator to check at beginning of experiment that the magnets are firmly in place in the wooden "molecules". Do not use if magnets are not firmly in place.
# 7. Demonstrator should be aware of any breathing changes, rash, runny nose, or choking that occurs to them when they are near the locusts, and should not perform experiment if they get these symptoms. Demonstrator should also be aware of the possibility that others may be allergic/get an asthma attack.
ACTION TO BE TAKEN IN THE EVENT OF AN ACCIDENT # 1. If glowstick contents come in contact with skin, rinse immediately. If they get into an eye, demonstrator must call a first aider and may perform an eye wash if trained and confident to do so.
# 2. If cold solution is spilt onto anyone rinse off with copious cold (but not freezing cold) water. Call a first aider in the case of injury.
# 3. Turn off electric power at mains. Call first aider in the case of an injury/shock.
# 4. Call a first aider, who will consider giving an eyewash.
# 5. Call a first aider in case of injury. Bathe affected area under cold water for at least 10 minutes if you suspect a burn.
# 6. Call first aider in case of injury.
# 7. Do not demonstrate if you find yourself to be allergic to locusts. Call a first aider in the event of anaphylaxis or asthma attack. Calm person down, sit them down. Get person to use inhaler if they have one. Call 999 if person is choking as part of an anaphylactic reaction.

Dry ice risk assessment

DESCRIPTION Generally using Dry ice.
RISKS # 1. Dry ice is very cold. There is a risk of cryogenic burns if it is handled.
# 2. There is a risk of asphyxiation if large amounts of gas are produced in a confined space.
# 3. The dry ice could be stolen and used irresponsibly.
# 4. Confinement of dry ice in a sealed container could cause it to burst, possibly explosively.
# 5. Production of large amounts of steam in a confined space could reduce visibility, causing accidents.
ACTION TO BE TAKEN TO MINIMISE RISKS # 1. Do not allow visitors to handle the dry ice; watch children carefully. Ensure that the box is strong, stable and under the demonstrator's control. Demonstrators must use insulating gloves when handling dry ice. These must be provided.
# 2. Do not use in very confined spaces, or allow anyone to hold their head over the box for long periods.
# 3.The box containing the dry ice should be kept under the demonstrator's control, and closed when not in use. Watch children carefully.
# 4. Never seal dry ice in a container.
# 5. Do not produce very large quantities of steam indoors.
ACTION TO BE TAKEN IN THE EVENT OF AN ACCIDENT # 1. In the case of a cryogenic burn flush with tepid water (not warm) then cover with clean plastic and wrap in warm clothing (do not allow fabric to touch burn). Call first aider. Ensure that medical advice is sought promptly if the burn is severe (A+E).
# 2. Take casualty outside. Call first aider. Ventilate the area.
# 3. Find a lost box of dry ice as a matter of urgency. If someone has received a cryogenic burn or other injury from misusing stolen dry ice, treat as in (1) or as appropriate.
# 4. Call first aider in the event of injury.
# 5. Ventilate the area. Call first aider in the event of injury.
This experiment contains mains electrical parts, see separate risk assessment.
This experiment is sometimes run in a darkroom, see separate risk assessment.
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