Bend a pencil without magic.

Transcription

1 Bend a pencil without magic. What you need: Pencil Water Clear glass Activity: Half a fill a glass with water. Place the pencil in the water. Look at the pencil from the top. Now look at the pencil from the side. Does the pencil look bent? Think the light is playing a trick on your eyes? Well it is!

2 Bouncing raisins What you need a tall clear glass or jar water vinegar baking soda eight or more raisins Activity: Begin by half filling your glass or jar with water. Then add the vinegar and baking soda to the water. The mixture in the glass will begin to fizz. Drop the raisins one at a time into the glass. The raisins may initially sink to the bottom but eventually they will rise up and then sink, then rise again. Children should be able to watch the raisins bounce for up to an hour

3 Floating coloured water experiment What You Need: Two glasses Salt Food colouring Water Spoon Activity: In the first glass, add a couple of teaspoons of salt. In the second glass, add several drops of food colouring. Slowly pour in warm tap water to both of the glasses. Stir the salt water until the salt dissolves completely and stir the food colouring in the other glass until the food colouring mixes. Slowly pour the coloured water into the salt water glass. Watch to see how the coloured water rises to sit above the salt water. Notes The coloured tap water will sit above the salted tap water because salt water is heavier than tap water

4 Make an egg that bounces What You Need: Egg Plastic cup Vinegar Plastic spoon Paper towel What to do. Place an egg in a plastic cup and completely cover with vinegar. Place the cup somewhere where it doesn't have to be moved for four days. The vinegar will dissolve the eggshell. After two days, use a plastic spoon to remove the egg from the cup. Lay it down on a paper towel so that it can dry. The eggshell will have completely dissolved. Take the egg outdoors and from a low height gently bounce it. Notes Osmosis is the process where water passes into tissues through a semipermeable membrane

5 Match in a glass experiment What you need: Blu-tack, playdough Match Plate Highball glass Water Food colouring (optional) What to do. Use the blu-tack or playdough to stick the unlit match, upright to the plate. Pour a moat of water around the match (you can colour the water with food colouring to make it more fun if you want!). Get an adult to light the match for you. Quickly place the glass over the top of the lit match. Watch as the water is sucked into the glass. Why is it so? The match creates hot air inside the glass. The difference in air temperature between the inside of the glass and outside the glass causes the gas inside the glass to push against the glass. This causes a vacuum effect. When the match starts to go out, the air cools and the pressure is released, sucking the water inside the glass

6 Mentos in Coke experiment What you need: 1 x bottle of cola (diet cola works best) 1 x bottle of lemonade (or any other soda) 1 x packet of mint Mentos An outdoor area you can hose down afterwards it's an old trick: drop a Mentos into a bottle of Diet Coke and "whoosh" a sticky brown geyser shoots up out of the bottle. To find out why it happens, you can explore a few variations: will it happen with any type of soda? does it only work with diet sodas? does it only work with white mint Mentos? For the record, we tried it with both diet and full sugar sodas. It worked with both, but the diet soda produced a bigger reaction. We tried it with cola and lemonade. Both worked. We also tried it with coloured mentos and mint Mentos. Again, both worked. Why is it so? There are many explanations for this phenomenon. Here is one abridged version: A bottle of soda is full of carbon dioxide (the bubbles.) The bubbles stay suspended in the liquid until the bottle is opened. When you drop any sort of object into a bottle of soda, bubbles form on the surface of the object. This is called, "nucleation." Add to this the fact that the surface of a Mentos is textured: it's made up of lots and lots of tiny craters. These tiny pits create a larger surface area and essentially provide many more "nucleation sites."

7 The Mentos drops to the bottom of the bottle, forming lots and lots of bubbles on its pitted surface along the way. When all of this gas is released it forces the liquid up and out of the bottle in a giant whooshing geyser of sticky soda. Why does it work better with diet sodas? No one has worked out why. But what they have worked out is: diet sodas are less sticky to clean up!

8 Make a lava lamp What you need: clear plastic bottle with lid vegetable oil water food colouring Alka-Seltzer tablet Fill the bottle three quarters of the way with vegetable oil. Fill the rest of the bottle with water that has been coloured with food colouring. Close the bottle lid tightly. Wait for the two layers to settle. Break the Alka-Seltzer tablet into small pieces. Drop small pieces of the tablet into the bottle to create a bubbly fizzy lava lamp.

9 Colourful milk swirl experiment What You Need: 1 cup full-cream milk (skim milk contains too much water to be effective with this experiment) 4 different food colourings (you have to use the standard ones, natural ones are not as concentrated and so don't work as well) Dishwashing liquid A medium-sized bow Pour the milk into the bowl. Place one drop of each of your colours into the milk, keep the drops close together. Add a drop of dishwashing liquid to the mix. Watch the colours swirl around. Why is it so? The fat and protein molecules in the milk are altered by the soap. This causes them to roll around. Once the soap molecules have mixed evenly with the fat and protein molecules in the milk the motion will stop. So keep adding drops of dishwashing liquid when the action slows down

10 Easy bubbly colours experiment What You Need: 4 large tablespoons of bicarb soda (or baking powder) 1 cup white vinegar 4 different food colourings ('natural' ones are not concentrated enough so stick to the evil chemical version) Muffin tin Teaspoon An outside table (or an inside table with lots of newspaper laid down to catch the mess.) Ideally, set this experiment up outside, because to make it work properly it has to get a bit messy and bubble over. Depending on how many colours you have, use a different muffin cup for each colour. We used four colours. So start by half-filling each muffin cup (in our case four muffin cups in total) with vinegar. Now put one drop of each colour into a different cup of the muffin tin. Now plonk one heaped teaspoon of bicarb into each cup and watch the colours fizz! Why is it so? The acetic acid in the vinegar reacts with the sodium bicarbonate to form carbonic acid. The carbonic acid is unstable and immediately falls apart into two components of carbon dioxide and water. The carbon dioxide escapes the water as gas. It

11 bubbles up and then, because it's heavier than air, it sort of falls down again, flowing like water over the edges of your muffin tin.

12 Blackcurrant tea in water What you need Plastic cups Blackcurrant tea bags. What to do Give chn a plastic cup half filled with water. Ask children to tear open a blackcurrant tea bag and add to the water. What do they notice? What is happening?