Take the Fab Science fun home to your kitchen!
We’ve put together some ideas for things you can try at home, keep checking back as we’ll be adding more. You don’t need any special equipment, we’ve used beakers from the lab but plastic cups will be just fine! All experiments should be done under adult supervision and you should judge whether the activities are suitable for your child. Always read labels on any household chemicals for safety precautions and wear goggles when using anything that could irritate the eyes. Don’t forget science can be messy so take care to protect clothes and surfaces!
Simply fill a small white plate with water (a few millimetres deep) and place a selection of Skittles or M&Ms around the edge. Keep it very still and watch as the colours travel across the plate. What do you think will happen when the colours meet? You might expect them to mix but you’ll probably find that you get perfectly neat lines instead! This is because the sugar and colouring that is dissolving from the surface of the sweet is spreading out by a process called diffusion. The sugar will move from where there is lots of sugar to places where there is less. When it meets more colour and sugar coming the other way, there’s no point going any further!
You may have already seen or heard about the Coke and Mentos experiment. Basically you drop some Mentos in a bottle of Diet Coke and stand well back as it makes a big fizzy mess! First, you need to know what is going on. Fizzy drinks are just flavoured drinks that have a whole load of carbon dioxide gas dissolved into them. The gas stays trapped inside for as long as the lid is screwed on tight, when you take the lid off it will slowly come out as small bubbles. This is what makes the drink ‘fizzy’. If you’re a very patient person who really like watching bubbles, you could sit and watch it for a couple of days while each bubble gradually makes its way out. I’m guessing that you would like something a bit more dramatic! By dropping things into the bottle, you can get all those bubbles to form at once and rush out of the bottle in a big fountain. The most famous example is the Mento but it is not the only contender for best fizz-producer. You can try out other sweets, salt, sugar, cake sprinkles…whatever you have in the cupboard. Try different drink brands and flavours, which is best? Don’t waste your money on expensive drinks, I’ve had great results with the cheapest supermarket brands.
Two very important things that you need to know: (1) This is an OUTDOOR experiment!!! It makes a big mess so make sure it is on the grass or somewhere that spillage doesn’t matter. (2) Only use sugar-free drinks, they simply work better (and don’t leave a horrid sticky mess that will attract every ant in the world to your garden). You might like to make a cardboard tube ‘launcher’ so you can drop several sweets in at once. Be warned it ‘erupts’ pretty quickly so stand back!
And … do this outdoors (did I mention that?).
The internet is full of recipes for slime, goo, science putty, fake snot…whatever you want to call it. Unfortunately they usually have ingredients that are readily available in the States but trickier to get hold of here (unless you are a school or a Fab Scientist!). So I was over the moon to see that one of the fantastic Bishop’s Stortford mummies had shared a new recipe on Facebook that you can try at home. Here it is:
You need: PVA glue, Aldi Almat laundry gel (I used the one with the purple lid), a plastic cup, food colouring
Fill a third of the cup with glue, add a couple of drops of food colouring (not too much) and stir. Now add the washing gel a little at a time, stirring in between until you get the consistency that you want.
So what’s going on?
Everything is made of molecules and there are so many different types of these molecules. PVA glue is a polymer which means it has really long molecules, like microscopic spaghetti. They easily slide over each other so the glue is quite runny. The borax in the laundry gel makes cross-links which join these spaghetti strands together so they can’t slide so much anymore. The more gel you add, the less runny the slime is.
Bad hair day
For this experiment you need some hair gel. None of your fancy styling wax or re-mouldable gum, just old-fashioned gel (the Tesco Value one works perfectly and is ridiculously cheap). Do this over this sink!
Scoop some up in your hand, what does it feel like? Hold the gel in your hand (over the sink) and sprinkle some salt on it, what happens?
Think like a scientist:
- Is it any different with dishwasher salt?
- Or a different type of gel?
- What would happen if you sprinkled salt on Jedward?!?
Gooey fun with Oobleck
Oobleck is simple to make but the most messy fun you can have with your kitchen ingredients. All you need is some cornflour and water, about a cup of water mixed with a cup and a half of cornflour works well. You can add a bit of food colouring if you like. Green is slimetastic but go with any colours you fancy, pink and glittery can be lots of fun.
Now to experiment…
Try to decide if the Oobleck is a solid or a liquid. Try to press it hard, solid or liquid? Try pouring it, solid or liquid? It’s actually neither, it has a fancy scientific name of a ‘non-Newtonian fluid’, this means it can behave like either. Try stabbing it hard with a spoon, suddenly it’s solid, let the spoon rest on top and it sinks. Weird, huh? You can squeeze it into a ball, it feels all hard but as soon as you let go (or hand it to an unsuspecting victim!) it will collapse and go runny. Make up your own experiments, get your hands in it, get gooey and have fun. When you’re done, leave it to dry and keep for another day (don’t use it in the gravy though!).
The Oobleck gets even more odd if you get them vibrating. I’ve put some on an old speaker (covered in clingfilm) and played some loud music through it. If you get the right sounds, the oobleck will start to jump and dance about. If you want to see this without risking your speakers, I’ve put a video clip of this on the Fab Science Facebook page. There is also an amazing video here of people who have taken the oobleck experimenting to the extreme by filling whole swimming pools with it! Strangely it is an advert for a bank but it’s a pretty cool video. Notice what happens when they stop running or jumping, they will sink. You can try this with your oobleck in a dish, try ‘running’ across it with your fingers, then ‘standing still’.
So what’s going on?
The tiny bits of cornflour have jagged edges, when you press them together they get stuck and can’t move past each other, so you have a solid. If you stop pressing, they come unstuck and can flow again like a liquid.
You can make your own colour-changing potion just using vegetables! You will need a grown-up to do the cooking bit.
Making the potion:
Roughly chop half a red cabbage and boil in just enough water to cover it for around 10 minutes. The water should turn dark blue. Keep the water and put the drained cabbage to one side. Leave it to cool.
Doing the experiment:
You need some beakers (see-through ones are best). Put about 100ml of water in each one and add 2 tablespoons of the blue potion. Now get experimenting! Try adding different things to see if you can make the liquid change colour, you’ll need to give them a stir. Things you could try: vinegar, lemon juice, milk, liquid hand soap, toothpaste, bicarbonate of soda, washing powder… anything else that you can find (check it’s safe!). Try it again using beetroot instead of cabbage, do you get the same results?
Think like a scientist:
- Try to guess what colour each one will go before you do it.
- Can you change the colour back if add something else?
- Have a look at the cabbage, what colour is it? Would you want to eat it? How could you make cabbage stay red when it’s cooking? (look up red cabbage recipes for the answer!)
- The colours change because the things that you are testing are called acids and alkalis. Acids turn the liquid red or pink, alkalis make it go blue or purple. Can you find out about them in books or online?
Let’s get fizzy-cal!
The best ingredient for having fun with kitchen chemistry has to be bicarbonate of soda. Mix it with any acid and see it fizz away, making lots of carbon dioxide gas. The cheapest safe acid to use is vinegar but lemon juice can also be used in either of these experiments. More expensive but smells better!
You need: a balloon, an empty plastic bottle, vinegar and bicarbonate of soda. A funnel is also useful but you can make one out of rolled up paper if you don’t have one handy. Pour vinegar into the bottle and put a couple of spoonfuls of bicarb in the balloon (this is where the funnel comes in). Then carefully stretch the mouth of the balloon over the top of the bottle without letting any powder fall in. And then….nothing will happen. The reaction can’t start until the powder mixes with the vinegar, just tip the balloon (not the bottle!) and watch as your balloon inflates by ‘magic’. Try experimenting with different amounts of vinegar and bicarb, different sized bottles or different acids (for example, apple, orange or lemon juice). Which is best?
Exploding sandwich bag
This one is fairly similar to the magic balloons but much messier and should only be done outdoors. You need: a small ziplock bag, vinegar, bicarbonate of soda and one square of kitchen roll. Wrap a couple of spoonfuls of bicarb in the kitchen roll to make a little parcel. Then quarter fill the bag with vinegar. Now for the tricky bit: hold the parcel of powder at the top of the bag (not touching the vinegar) while you close the zip. The reaction will start when you drop the parcel into the liquid. Gas will be made, the bag will inflate and then…bang! The bag will burst with the pressure. By this time you need to have put it in the garden and be standing back to watch. If it doesn’t work, try changing the amounts of vinegar or powder or use a different sized bag.
You are what you eat!
Eat your greens! No more sweets! Drink your milk! No fizzy drinks! Parents are always telling us what to eat but why? Investigate food packaging to find out which foods contain lots of sugar or plenty of good stuff like calcium and fibre. If you have access to the internet, you can experiment with making the healthiest and unhealthiest meals on the McDonalds nutrition calculator. Try out these investigations at home to see what happens if we don’t have enough calcium in our diet or eat too much sugar.
A trip to the dentist
Firstly, let’s look at what different drinks do to our teeth. If you can convince the tooth fairy to leave your teeth behind in the name of science, you can use real teeth. Otherwise, hard boiled eggs are a good substitute*. Pop each one in a plastic cup with a different drink; sugary cola, sugar-free cola, orange juice, fizzy water, tap water, anything you like. If you really want to see what acid does to your teeth, try putting one in vinegar! You might not think that you’d drink vinegar but bacteria in your mouth turn sugar to acid, so sugary things end up being acid in your mouth. This is why it is so important to brush your teeth! Leave the teeth or eggs in the drink for a week and then have a look for any changes.
Want to see what happens to bones when they don’t have calcium in? Try bending a clean chicken bone to see how stiff it is, then pop it in vinegar for three days. Rinse it off and try bending it, has it gone all rubbery? Can you explain why?
*Note for super scientists: are eggs really a good substitute for teeth? Of course your teeth are much stronger than the eggshells but they are made of a similar material. The egg shells contain mainly calcium carbonate while tooth enamel is mainly calcium phosphate but both dissolve in acid.
Kids love any excuse to play with water. If we have a ‘BBQ summer’, get the paddling pool (or just a big tub) out in the garden and encourage your child to investigate what floats or sinks. If the summer is less summery, the bath or kitchen sink are just as good! Interesting things to try are: cotton wool balls, cans of diet and normal Coke, candles, any types of food, seeds, leaves, plastic toys etc. Try a ball of plasticine. Can you make it float by changing the shape?
Think like a scientist:
- Why would some cans of coke float and others don’t (look at the sugar content)?
- What are the best shapes to float? Try them out with plasticine.
- Why do seeds and nuts need to float?
Gloopy floating and sinking
You can extend the floating and sinking idea by finding out what floats in different liquids (be warned: this can get messy!). Try to find things that sink in water but float in a beaker of denser liquid such as golden syrup or washing up liquid. Or what about things that float in water but sink in cooking oil? Some ideas to try: conkers, olives, peas, marbles, plastic buttons.
This is one of my personal favourites. Using the ideas of density in liquids from the gloopy floating and sinking experiment, you can make liquids float on top of each other. You need a glass or clear plastic beaker. First, pour about 1cm of golden syrup in the bottom (this is easiest if you buy the syrup in a squeezy bottle). Try to avoid getting any on the sides of the glass. Next, carefully pour washing up liquid on top (try to pour it very slowly down the side of the glass). Do the same with some water, even slower this time (I like to add a little food colouring to make it prettier). Finally pour vegetable oil slowly onto the top, it’s easier if you run it over the back of a spoon. Hey presto, you’ve made a liquid rainbow, isn’t it pretty?
Think like a scientist:
- What happens if you carefully pour water on top of your rainbow? (watch from the side)
- Can you experiment with other liquids?
- You can make your own liquids of different densities by adding different amount of salt to water.
What happens when you poke a balloon with a sharp stick? Expecting it to go bang? Try out this fab science trick to skewer a balloon without popping it (hopefully!).
You will need: balloons, bamboo skewers, vegetable oil.
First, inflate the balloon about half-way and tie a knot. Next, dip your skewer in oil to make it easier to push into the balloon. Now for the important part, choosing where to stick the skewer: look carefully at the balloon and you’ll notice that the area close to the knot is a little darker than the rest of the balloon, that’s because the rubber isn’t stretched as much. This means that if you make the hole there you might manage to avoid the ‘pop’. At the other end, there is another darker area, carefully push the skewer out at that point and you have a balloon kebab!
Note for parents: take care with sharp points and this should only be attempted under supervision. A cheap pair of safety goggles from a DIY store could come in handy.
Roll the Blu-tack into a sausage and use it to attach the cap the centre of the CD. Make sure the cap is closed. Inflate the balloon but don’t knot it, then carefully stretch the opening over the bottle cap (it helps if you twist the end of the balloon to stop it deflating while you’re doing this). Your hovercraft is now ready to go! Carefully open the cap and the air will start to escape from the balloon. This makes a ‘cushion’ of air under the CD so you should be able to skim it along a smooth surface (the floor is best). Why not decorate your hovercraft and race it against your friends?
Think like a scientist:
- Try skimming it without the balloon (or with the cap closed), what do you notice?
- The cushion of air reduces friction between the CD and the floor, can you find out more about friction?
- Does the size of the balloon make a difference?
Tricking your senses
Have you ever tried to trick your own brain? Try these experiments to find out about your senses.
Where did you hear that?
When you hear someone speak, you don’t just hear what they are saying. You can also tell where they are. Trick your ears by making this simple ‘Ear Switcher’. All you need is about a metre of hosepipe, a couple of funnels and some sticky tape. Cut the hose into two pieces, stick a funnel in the end of each one, then tape it together as in the picture. If you have a plastic Alice band, stick the whole thing on that to make it easier. Pop it on your head and hold the free ends of the tube in your ears (never stick anything right into your ear!). Now close your eyes and get someone to make noises, can you work out where they are? We normally work out direction because sounds reach one ear before the other. Sound travels super-fast (over 700 miles per hour) so there is only about a two-thousandth of second between hearing it one ear and then the other. You brain is clever enough to notice that difference and use it work out a direction….until you confuse it with an Ear Switcher!
Want to see right through your hand? For this experiment you need an old kitchen roll tube, your eyes and hands. Have the tube in your left hand, carefully hold it against your left eye. Now put your right hand in front of your right eye, with your palm towards you and the side of your hand touching the tube. Keep both eyes open. Slowly move your hand away from you, along the side of the tube. You should see a hole in your hand! Your brain is used to ‘stitching together’ the pictures it gets from each of your eyes, this makes it look as if the tube goes through your hand!
Take care when putting tubes near eyes and ears.
Coloured icebergs and flipping water
The next couple of experiments could be a celebration of icy weather or fun outside in the summer sun. Make your ice outside in the garden if winter gets cold enough or it’s just as good from your freezer.
First, make some coloured ice-cubes by adding food colouring before freezing. You can freeze them outside if it’s cold enough. When they’re frozen, you’re ready for the next bit. Half fill a tall glass with water and add a layer of vegetable oil on the top (about 5cm). If you drop in a coloured ice cube, where does it go? What happens as it starts to melt?
Another experiment using the same ideas is ‘flipping water’. Half fill a plastic beaker or tub with coloured water and add a layer of oil on top. Leave it outside to freeze (or pop it in the freezer), what happens to it? You should see the layers have switched round. If you do this in a freezer, make sure the tub has a lid!
Think like a scientist:
- This experiment is all about density (how heavy something is for its size), things that are less dense float on top of things that are more dense.
- Which is more dense, the oil or the ice? The oil or the water? The water or the ice?
- Ice floating on top of water is handy for keeping your drinks cool but very important for fish and other things that live in water. Otherwise ponds, lakes and the sea would freeze from the bottom up, killing all life in the water.
The snowman’s coat
What happens when you put a coat on a snowman? A coat can keep you warm but it would also keep a snowman cold! Try out an investigation to find out the best way to stop a snowman melting. Ask an adult to help you find some materials that you could use, maybe a tea-towel, any old clothes, an old scarf, bubble-wrap, newspaper…be creative! Now to make your snowmen; if it’s snowing you can make real ones or otherwise make them in the freezer. You could cover a gingerbread-man cutter with cling-film, fill with water and freeze to make ice-men, or perhaps make ice-hands by freezing rubber gloves that have been filled with water. Stand your men (or hands!) in a deep tray (big enough to catch all the water as they melt) and wrap them in different ‘coats’. Which one do you think will be best? Keep checking to see if you are right.
Think like a scientist:
- Can you predict which will be the best?
- Materials that keep things warm or cold are called insulators, can you think of other uses for them?
- Can you find out what the opposite of an insulator is?
Volcanoes hold great fascination among children (and grown-ups!). Here are some ideas for making your own and experimenting with the best eruptions.
First you need to find out about volcanoes. Do you have any books about them? Try looking up ‘volcano facts for kids’ on the internet. There are some great pictures and videos available too. Do you want to make a cinder cone, stratovolcano or shield volcano? Then think about what to make it out of. You could use sand, salt dough, paper mache, Lego, junk…be creative. It will get messy though! Whatever you make it out of, it needs to be on a big tray to catch the ‘lava’. Put a small bottle inside to be the ‘magma chamber’, make sure you don’t cover the top of this.
Experimenting with eruptions
There are a few options for making your volcano erupt. You can try them out (on a tray or in the sink!) before choosing one to go in your volcano model.
The most common is vinegar and bicarbonate of soda. Just mix a tablespoon or two of bicarbonate of soda with about a cupful of warm water. Pour it into a small bottle, add a squirt of washing-up liquid and then vinegar. You can experiment with different amounts of vinegar and powder.
Or try a mini version of Coke and Mentos. Take a small (250ml) bottle of diet cola, drop in three Mentos and decide if that’s the eruption for you!
My favourite is a much slower eruption but it just keeps on going for ages. This one needs some 6% hydrogen peroxide (available cheaply in all chemists, don’t use any stronger than 6%). Pour 100ml into a small bottle, add a good squirt of washing-up liquid and then add the magic ingredient: a spoonful of yeast mixed with warm water. The foam ‘lava’ is safe to play with, it’s just soapy water.
How do these work?
- The vinegar and bicarbonate of soda react together because they are an acid and an alkali (see the colour changing cabbage experiments for ideas about this). The chemical reaction makes a type of salt, some more water and carbon dioxide gas. It’s the gas the makes it into an eruption, the washing up liquid just catches some of this gas to make a load of bubbles.
- See the Fizzy Fountains experiment for ideas about Coke and Mentos.
- The final eruption is called ‘elephant’s toothpaste’ as it looks a bit like a massive heap of toothpaste being squeezed out of a tube. The hydrogen peroxide can break down to make water and oxygen gas. It usually happens pretty slowly but the chemicals in yeast speed it up. All the gas bubbling up through the washing up liquid is what makes all the foamy fun!
Make your own bath bombs
These bath bombs don’t actually explode but they will fizz away when you put them in the bath. All the ingredients can be found in your kitchen/bathroom cabinet or can be bought in the supermarket (except citric acid which you can find in a chemist or homebrew section, I picked some up in Wilkos for 75p).
You will need: Corn flour (2 tablespoons), Citric acid (2 tablespoons), Bicarbonate of soda (4 tablespoons), Oil – coconut or olive are good (1 tablespoon)
Optional extras: Food colouring, Fragranced oil/perfume (check it’s safe on skin), A few dried flower petals (crushed)
What to do:
Mix the corn flour, citric acid and bicarbonate of soda together in a bowl (and flower petals if using). If you want to use fragrance and/or colouring add a few drops to the oil in a plastic cup. Then add the oil slowly to the dry ingredients, mixing in between. You may need add a bit more oil if it doesn’t form a paste (not too much though). When it’s nicely mixed, shape it into balls and leave them to dry on greaseproof paper. They’ll be fully dry in a couple of days then store them in an airtight tub. Pop the balls into cupcake cases and people will think that you have made lovely, thoughtful gifts, not just had fun with science J
What’s going on?
The bicarbonate of soda and citric acid will form a chemical reaction, making lots of carbon dioxide gas. This gas makes the fizzing and bubbles that you see when the bomb is dropped into water. The chemicals can’t react together when they are dry so the fun only starts in the bath!
Do play with your food!
We’re always told not to play with our food but sometimes it’s tricky not to! Here are some interesting investigations on food and our sense of taste.
Everything tastes the same!
Investigate how your senses of smell, taste and sight work together to help you enjoy your food. Get a few different fruits or vegetables such as carrot, apple, potato, turnip, parsnip or pear. Either grate or chop them into small pieces (all about the same size). Now get a volunteer to close their eyes and hold their nose while you feed them a little of each. Can they work out which is which? They probably can’t as you need all of your senses for your brain to identify a food. You could try different foods or different people (are adults or children better at this?). Apparently even strong-tasting foods such as garlic don’t taste any different from a potato if you hold your nose but I’ve never been brave enough to try! You could try chewing a small piece of raw potato while sniffing a piece of apple, does it start to taste of apple?
A boring old piece of celery can teach you lots about how plants work. Plants do not have veins and blood like us but they do have a system to move things around. They have special tubes called xylem vessels to carry water up from their roots to their leaves. You can see this in action if you put a stick of celery in a glass of coloured water (use food colouring). After a couple of hours you will see the colour has moved up the stem. If you cut across it, you will be able to see the xylem vessels clearly. You could try splitting the base of the celery stick and putting each half in a different colour do the colours mix or stay on their own sides? Try looking at other veg when you’re eating, can you see the xylem vessels in a carrot or lettuce?