FUNTIMES HOME EDUCATION

National Science was held in Cambridge during March this year.  The website associated with this event is still available to look at - here.  We went along to see some of the exhibitions and found, through the rain and cold and crowded rooms, that what we saw was good fun and most of it was free too.  Some of the things we did during our visit were:-

• Blow painting on a huge sheet, or hand printing if the children were more likely to suck than blow the paint! 
• Discovered the small brain size of some dinosaurs and looked at fossils. 
• Watched a good sized plastic volcano explode and studied models of volcanoes and how they operate. 
• Marvel at people dressed as interesting and beautiful characters high up and very steady on stilts.

After the event we browsed through the numerous science experiments listed on the website above and decided to make Rainbow Fish.

What's needed:-

Red cabbage
Water
Coffee filter paper
Vinegar
Bicarbonate of Soda
Paintbrush

Place the cabbage in some hot water to release the purple colour.  Remove the cabbage and place a coffee filter into the purple water.  Let is soke for a short while then take it out the water and leave to dry.  When dry, cut the filter into the shape of a fish.  Use a paintbrush dipped in vinegar to paint on the fish.  Add alittle water to the bicarbonate of soda to make it more liquid and paint this onto the fish too.  The fish should show different colours once you start to paint them.  When finished we added eyes and stuck our fishes onto a background photo of a cut red cabbage which had been "liquidised" using Photoshop on the PC.

The chemical anthocyanin in the red cabbage works with the other chemicals to indicate if it is acid or alkali.  We found out that vinegar is acid and combined with the anthocyanin turned the fish red.  The bicarbonate of soda is alkali and combined with the anthocyanin turned the fish blue.

(work: March '06)

We love doing these and make explosive volcanoes over and over!

We first tried a volcano experiment in October 2005 - it was our first real taste of science and I think it got us all hooked!  We had been doing a small project on volcanoes - why and how they erupt etc., so this was a perfect ending to it all.

Mini Volcano  

Use a small dish (if it has a raised edge, all the better).  Place an empty eggcup in the centre of the dish then carefully place flour around the dish building it up the edges of the eggcup, but make sure it doesn't spill inside the eggcup.  Put alittle baking soda (which is bicarbonate of soda, although baking powder did work) in the bottom of the eggcup along with a tiny amount of red food colouring (to add to the overall effect), then pour in some vinegar to see the volcano "erupt".  We found if you kept adding vinegar the volcano will continue to spew it's "lava".  If you leave the pinky "lava" to dry, it looked like rock cyrstals.

This experiment lead to ...

Another kind of explosive volcano  

We used a used, clean, glass salad dressing bottle (or a ketchup bottle) with enough baking soda to cover the bottom of the bottle, squirt in alittle washing up liquid too.  When you're ready, quickly pour in about 90ml of vinegar (tilt the bottle so it's only hitting a small amount of the soda).  It'll start to bubble!  Place your hand over the top of the bottle and wait until you can feel the pressure building (you could shake it abit too!).  Let go and jump back as the "lava" shoots out the bottle.

Finally we found this brilliant (thanks to "Discovery Kids" on TV) ...

A really explosive rocket!  

You'll need an old film canister with a click on lid (we picked some up from a recycling store, but try film processing companies who may have one or two spare).  Make a rocket by wrapping thin card or paper around the cannister ensuring the lid section is poking out the bottom (as you'll need to access this quickly).  Decorate the rocket as you wish.  When ready, wrap a small amount of baking soda inside a piece of toilet tissue and tape it inside the lid of the cannister.  Hold the rocket bottom upwards and pour vinegar inside the cannister (about just under half full seemed the best for us).  Probably best to go outside at this stage and find a suitable area to let off the rocket, away from breezes that'll knock it over, and on a flat surface.  When you're ready, quickly click the lid onto the cannister and turn the rocket so the cannister is sitting lid down on the flat surface.  STAND BACK!  In a short time, the rocket will fly into the air with a pop as the soda mixes with the vinegar and the built up pressure shoots off the cannister lid.  IF THE CANNISTER DOESN'T FLY - wait alittle longer, the mixture may be taking longer to produce enough pressure.  DON'T GO BACK TO THE ROCKET IF IT DOESN'T GO OFF, it may suddenly "explode" and hit you. 

Over time we discovered that using white wine vinegar rather than malt vinegar gave a very explosive result, as witnessed at a group HE session recently (the force shot the "lava" all over the ceiling!).

Following on from the explosive experiments shown on the page above, we thought it would make sense to have a look at forces in general. 

Did you know?  The strength of force is measured in newtons (N) (named after Sir Isaac Newton).  Everthing on Earth has weight and the force of gravity pulls everything downwards.  When we weigh things, like cooking ingredients or fruit and vegetables at the market, we use kilograms or pounds, 100 grams mass has a weight of 1 newton (N) and 1 kilogram mass has a weight of 10 newtons.

Working with air pressure - try this:-

Fill a tumbler with water right to the brim and place a piece of card over the top.  Keep the card in place with one hand and hold the tumbler with the other hand.  Carefully keeping the card where it should be,  turn over the tumbler so it's upside down (best done over a sink - just in case!).  Let go of the card and air pressure should keep it in place acting as a seal to keep the air out of the tumbler and therefore hold the water inside.  

Air pressure used to make a rocket

I think my hubby and I had as much fun as the children with this one, but take care to follow the instructions carefully so you don't have any accidents!

We used a used large plastic lemondade bottle and stick a straw with several pieces of tape to the length of the bottle.  Find a cork that will tightly fit the neck of the bottle.  Use a sharp object to pierce a hole in the top of the cork (like a pair of compasses) and insert a football inflator in the hole right through the cork.  Pour enough water inside the bottle to cover the neck when tipped upside down.  Push the cork into the neck, ensuring the inflator is sticking out the top (you may need a smear of something greasy  to help you with this).  Slide some string through the straw and tie one end of string to something high (best done outside, so a tree or high washing line), and the other end secure very firmly to the ground.  The bottom of the bottle should be pointing upwards at about 45 deg.  Attach a bicycle pump to the inflator and start to pump.  Eventually the air pressure will cause the cork to pop out (and make the water spray you and those close by) and shoot the rocket along the line.  Fantasic fun!

Making fizzy sherbert to eat with a sticky lolly is really simple and great fun.

This recipe is enough for 6:-

50g icing sugar
Scant teaspoon bicarbonate of soda
Scant teaspoon citric acid
Lollipop or stick liqourice to dip

Mix all the powders together well and divide into six containers (or clean paper/plastic bags to get the sweet shop effect).  Dip your lolly or liqourice into the sherbert and suck - it is lovely and fizzy so don't have too much or you may well end up with a tummy ache!  Try dipping the lolly into ordinary icing sugar to see the difference between the two.

The fizz is caused by a reaction between the citric acid and the bicarbonate of soda (an alkali).  The reaction happens on your tongue and the dry ingredients mix with water from your mouth and create a gas that forms lots of little bubbles which make your mouth tingle.

This same reaction is caused when dropping a bath bomb into water.  Try make mini fizzy bath bombs using this recipe, although it takes some practise to turn them out like the one's available to buy in the shops!

1 part Epsom Salts
2 parts Baking Soda (bicarbonate of soda)
1 part Cornflour
1 part citric acid or absorbic acid
(as a guide, 1 part could be 1 tablespoon)

Mix these ingredients together well with a spoon.  Add a few drops of essential oil for a scented bath bomb and add a few drops of food colouring (but not too much or it may begin to fizz during mixing).  Next, add up to 1 part oil (baby oil, almond oil or coconut oil that has been melted are good to use).  Don't add too much oil as the mixture needs to be quite dry.  The recipe then states to add 2-3 squirts of Witch Hazel using  spray bottle, but we just strayed water.  Mix everything together with your hands until it just starts to hold together when pressed in your palm.  Press together to form a small ball, or individual smaller balls.  If they crumble add a couple more squirts or a tiny bit more oil.  Place the bath bomb or bombs onto a baking sheet and leave them to dry for a few days, then store in an airtight container to stop any moisture getting to them.  When ready, drop the bomb/bombs into your bath water to enjoy a coloured, sweet smelling, fizzy bath.  Just like the sherbert, the fizz is a reaction between the acid of the citric acid and the alkaline of the bircarbonate of soda when mixed with the water in the bath.

Another way to cause am immediate fizzing reaction is to add vinegar (an acid) to bicarbonate of soda.  Try this to make bouncing raisins!

4 tablespoons vinegar
3 tablespoons bicarbonate of soda
1 tall, clear glass or jar
Water to half fill the glass or jar
8 or more raisins

Combine the vinegar and the bicarbonate of soda with the water inside the glass or jar - it will begin to fizz as predicted.  Drop the raisins in one at a time.  They may sink to start with but soon they will rise to the surface, sink and then rise again.  They should continue to do this for some time.

By combining the vinegar and the bicarbonate of soda, carbon dioxide has been created which forms bubbles (like in fizzy drinks).  These bubbbles collect on the raisins and lift them up, but as they reach the surface, the bubbles escape and cause the raisins to sink again.

(work: March '06/Nov. '05)

During the festivities for Guy Fawkes Night, we found an interesting experiment to understand how fireworks produce different colours when they explode.

This experiment needs adult supervision as it requires a hot blue flame (a gas hob is good for this).

Collect several paperclips and straighten them out.  Hold the end of the paperclip with some pliers to protect your fingers and dip the other end of the paperclip into a container of water, then dip it into some salt (some of the salt should stick to the paperclip).  Holding the paperclip tight with the pliers and keeping all fingers and clothing away from the flame, hold the salted end of the paperclip in the flame.  The flame should change to bright yellow.  Dip the hot paperclip into the water to cool it (but you still must not touch it as you could still get burned).  With new paperclips, try the experiment again, but dip the watered end in boric acid powder to turn the flame green, and cream of tartar to turn it lavender.

Most of the light that comes from a flame is caused by solid particles burning inside the flame.  The yellow colour of a candle flame is caused by tiny bits of element carbon burning.  A blue flame does not contain solid particles and gives off little light.  By adding chemicals to the blue flame it produces different colours. 

The yellow flame caused by salt is due to the chemical sodium.  The green flame from boric acid contains boron and the creme of tartar contains potassium to produce a lavender flame.

Other colours can be produced by adding the following chemicals:-

Calcium salts - orange, salts of strontium or lithium - red, aluminium or magnesium metal - bright white.

(work: Nov '05)

Anyone who has studied the beauty of snowflakes will appreciate how wonderful crystals are.  We have come across a number of ways to try and produce fascinating crystals and have found that, so far, this version has worked the best for us.

We have also tried growing crystals on a shop bought Crystal Rock.  The rock was placed in a bowl and white wine vinegar was poured into the bowl to cover the rock.  After placing the bowl and contents in the airing cupboard to quicken the evaporation, tiny red crystals formed on the rock.

Links to sites covering this topic:-

http://www.ed.gov/pubs/parents/Science/crystals.html (different crystal growing experiments)
http://exploratorium.edu/complexity/exhibit/saltcrystals.html (lovely photos of crystals)

work: (Jan. '06)