Floating coins

Floating Coins Monday, 14th January, 2008Look at the two coins in this basin! The strange thing is that I only put one coin in the basin. Why can we see 2? We can see 2 coins because of the refraction of light. The coin is actually on the bottom of the basin but the water in the basin bends the light so it looks like there is also a coin floating on the top of the water.
We played a game. We tried to cover the coins at the bottom with other coins. It is so hard to do because the light is bent so we never really know where the coins are.

Lazy Coin

For this experiment you need a cup, a piece of cardboard and a coin.

When we flick the card, the lazy coin falls into the cup.

This is due to inertia. The coin stays where it is even though the card is gone. Gravity then causes it to fall into the cup.

Floating Needle

Things like a needle, a paper clip and a pin sink if you put them in water. We can get them to float by putting them on bits of tissue.

When the tissue gets wet and sinks, the needle and paper clip continue to float (the pin was too heavy). This is because the surface tension of the water keeps them floating.

Diving Drops and Sinking Feelings

Oil and water don’t mix. Oil sits on top of water because it’s lighter.

If we put syrup in the cup too it sinks to the bottom because it’s heavy. If we put a few drops of food colouring into the cup the coloured drops sit under the oil and over the water for a while, but will burst and sink to the bottom after a while.

Erupting Volcano

We put bread soda into a small bottle. (We also added red food colouring for effect, and wash up liquid for bubbles). Nothing happened yet.

Next Thomas poured in vinegar and the volcano exploded, sending out bubbly red lava. This is because bread soda and vinegar have a chemical reaction together, giving off lots of bubbles (of carbon dioxide).

Bug Spray in Room 5

January 8th, 20008

We got a cup of cold water and two straws. When we put one straw into the water the water comes up part way in the straw.

If we take the other straw and blow across the top of the straw in the water, the air in the straw in the cup gets pushed out, followed by the water which squirts outafter it. All sprays work in the same way.

Tissue Goal

We have a ball of tissue sitting in the mouth of a bottle. When we blow the tissue, it flies out of the bottle instead of being pushed in. Why?

When we blow at the tissue, most of the air goes around the tissue, hits the back of the bottle, and comes back out again (after bouncing off the back of the bottle). This pushes the tissue out of rather than into the bottle.
We can make the tissue ball go into the bottle, by blowing right at it using a straw.

Water Experiments with Senior Infants

Wednesday, 19th December. Some easy water experiments to try at home:
Make a Diver
We made a diver out of marla, and connected him to a pen cap with a paper clip and an elastic band.We can get the diver to sink by squeezing the bottle, and we can make him surface again by letting go.This is because the diver floats when the pen cap is full of air but he sinks when the air in the cap is compressed (from the squeezing) and the cap fills with water. Water in the lid is too heavy to keep the diver floating.

Bath Tricks
Water will spill out of a bottle if you fill it with water, put your hand on top, turn itupside down and then take your hand away.Water will not spill out of the bottle if you fill it with water, put your hand on top, turn it upside down under the water and then take your hand away.This is because the air pressure pushing down on the water in the basin is as strong as the water pressure in the bottle trying to get out, so the water in the bottle stays put.

We can get a card to stick on our bottle of water. When we turned the bottle with the card on it upside down and let go, the card didn’t fall off. Why not? Because the pressure of airpushing up on the card was as strong as the water pressure in the bottle so the water couldn't get out and the card stays put.

Water Walks Along a String
You can get water to spill sideways by pouring the water down along a string. The water holds tightly on to the string by surface tension and travels along the string instead of spilling straight down. Detergent Power
Our speed boat is floating on the water.We can break the surface tension of the water by squirting in some wash up liquid. When we do this the boat will shoot forward.
Water Races
Does water flow faster if you shake or squeeze the bottle?........….No, it doesn’t, but if flows faster if you make a tornado in the bottle by swirling the bottle of water.
Making a tornado is fun. You can make one by joining two bottles together with plumbers tape. Start the tornado by swirling the water in the top bottle. Making Boats
Does marla float or sink? Both. If it is in a ball it will sink but you can make it into a boat shape and it will float.We made boats and then when they could float we filled them with peas (passengers)Flat thin shapes with high sides seem to make the best boats.

An un-burstable balloon

Normally a balloon will burst if you prick it with a pin. We found a way to keep the balloon from bursting. If you put sticky tape on the balloon first, and then use the pin, the balloon doesn't burst at all, or it doesn't burst for a while. Our balloon didn't burst at first, but then it burst, giving us all a fright.

Red Cabbage and Acids

Teacher chopped red cabbage and put boiling water on top. The colour from the cabbage went into the water. We put this water into cups. We tried adding lemonade to one cup and wash up liquid to another. Both cups turned pink because of the acid. Soap turned the cabbage water a blue green colour so we know this soap is alkali.

Lemon turned the cabbage water pink. Lemon is acidic.

Our acids all turned the cabbage water pink or red. Our alkalis all turned the cabbage water blue or green.

Dancing Raisins

Raisins sink in water because they are so heavy….....but they dance in white lemonade.
This is because the bubbles in the lemonade stick to the raisins and make them float to the top. When the bubbles burst the raisins sink again.