From mentos in a bottle to playing with rainbows: science experiments children can do at home | Science
Children and adults alike may be stuck at home during Science Week this year, but that doesn’t mean the pursuit of knowledge has to be put on hold too.
Dr Karl Kruszelnicki told Guardian Australia that kids today might have access to a wealth of information with the internet, but getting hands-on takes the next step.
“Science is not a bunch of facts, that’s an encyclopedia,” Dr Karl said. “The beauty of doing physical experiments right at home is you can see it happen right in front of you and you know you are dealing with reality.”
“Science is a way to understand the world around you and if you do cute little experiments, you start understanding that there’s actually a little bit more going on around you than you think.”
Dr Erinn Fagan-Jeffries, a wasp expert from the University of Adelaide and the South Australian Museum, produced a show called Science and Magic that ran during Science Week in 2019 and at the 2020 Adelaide Fringe.
She said there were many simple ways to fire a child’s natural curiosity.
“When you work with kids, they’re born scientists because they love to ask questions and they don’t have fear of asking questions,” she said. “Which is really all that science is.”
For those looking for suggestions, Questacon has a host of fun science experiments on their website, but to make things easier we picked out a few of our favourites, ranked by difficulty – with a few recommendations by Dr Karl and Dr Fagan-Jeffries.
1. The classic: Geyser from a bottle
Add a Mentos to a bottle of carbonated fizzy drink and you have yourself a classic. As the carbon dioxide it creates builds up, the liquid will eventually cause it to erupt. Refreshing the trick to keep it new and interesting is easy: just add scale.
2. Keeping it simple: Egg in a bottle
Another oldie but a goldie: using a glass bottle with an opening just smaller than a hard-boiled egg, light a piece of paper, drop it inside and place a shelled hardboiled egg on top. Watch as the egg slips through the opening into the bottle.
Then, if you’re really good, use the same process to get the egg back out again.
Though it is simple, the experiment is a working demonstration of the relationship between the volume, pressure and temperature of the gases both inside and around the bottle. The egg creates a seal while the heat inside the bottle causes air pressure to build up until the oxygen inside can escape, reducing the amount of air inside the bottle. Because the air pressure outside the bottle doesn’t change, it gently begins to push the egg through the opening.
3. Fluid dynamics: Playing with rainbows
Stepping it up a notch – but not to the point where you’ll be playing with fire – this one needs a shallow dish, whole milk, some dye and dish soap. Place the milk in the dish, drop the dye into it and then place a drop of dish soap at the centre to watch a colourful tie-die effect sprawl. This happens due to the molecular mechanics of soap – finding out why makes for a good research project afterwards.
Other variants suggested by Dr Karl, include placing pepper in water and adding dish soap to watch it move. Another involves placing four M&M’s around the edge of a plate and then filling it with 90C water. While the dyes in the sugary shells dissolve into the water, the dyes mix but don’t intermingle.
“They start getting closer to each other, and then something happens! Then you ask yourself, why on earth did that happen?” he said. “Then you have to do the research to find out.”
4. Wow factor: Hot ice
This experiment requires a bit of kit but it is worth it – though it should only be attempted with parental supervision. We’ll leave it to the video to explain the process and the science, but it teaches how to make a supersaturated solution that instantly crystallises. In a twist, the “ice” it creates is hot rather than cold, demonstrating an exothermic reaction and the heat of crystallisation.
Once you master the basics, you can also try having some fun by making instant ice towers and flowers.
5. The dangerous: Hybrid rocket engine
The first thing budding engineers and rocket scientists learn is that there are three types of rocket engines: liquid fuel, solid fuel and hybrid engines that rely on both types of fuel. As it turns out, you can create your own simple hybrid engine using yeast, hydrogen peroxide and uncooked pasta. When the yeast and hydrogen peroxide are mixed together they create pure oxygen. Light the pasta on fire and you have yourself a basic rocket engine.
This is another one that should only be attempted with parental supervision and the instructional video below contains some important safety tips.
6. Bonus option: Get into the back yard
The other option is to get into the back yard to explore the natural world. Bush Blitz – Australia’s largest nature discovery program – has prepared a treasure hunt for Science Week that allows participants to look for new species in their back yards or on their walls.
“I’m a taxonomist, and I work on insects, so my science is less about mixing bicarb and vinegar together to see an explosion – which is fun. My science is about getting outside to see the ecosystem and understand our biodiversity. So the living things in the environment,” Dr Fagan-Jeffries says.
“We think that 70% of the animals, plants and fungi in Australia have not been described yet. They have not been discovered by western science and given a name which means anyone can find a new species – if they look hard enough.”
Instructions about how to participate can be found on the Bush Blitz website.