71 Science Experiments: Verify classroom knowledge with experiments

EXP-1

Make an Egg Float in Salt Water

An egg sinks to the bottom if you drop it into a glass of ordinary drinking water. But what happens if you add salt? The results are very interesting and can teach you some facts about density.

What you need

One egg, Water, Salt, A tall drinking glass.

What to do

Pour water into the glass until it is about half full.

Stir in lots of salt (about 6 tablespoons).

Carefully pour in plain water until the glass is nearly full. (Be careful not to disturb or mix the salty water with the plain water.)

Gently lower the egg into the water and watch what happens.

What’s happening

Salt water is denser than ordinary tap water; the denser the liquid, the easier it is for an object to float in it. When you lower the egg into the liquid, it drops through the normal tap water until it reaches the salty water. At this point the water is dense enough for the egg to float. If you were careful when you added the tap water to the salt water, they would not have got mixed, enabling the egg to amazingly float in the middle of the glass.

EXP-2

Melting Chocolate

Enjoy this simple melting chocolate experiment. You’ve no doubt experienced chocolate melting on a hot day, so let’s do some experiments to recreate these conditions as well as a few others before comparing results and coming to some conclusions. At what temperature does chocolate melt from a solid to a liquid? Is it different for white and dark chocolate? Give this fun science experiment a try and find out!

What you need

Small chocolate pieces of the same size (chocolate bar squares or chocolate chips are a good idea), Paper plates, Pen and paper to record your results.

What to do

Put one piece of chocolate on a paper plate and put it outside in the shade.

Record how long it took for the chocolate to melt, or if it wasn’t hot enough to melt then record how soft it was after 10 minutes.

Repeat the process with a piece of chocolate on a plate that you put outside in the sun. Record your results in the same way.

Find more interesting locations to test how long it takes for the chocolate pieces to melt. You could try your school bag, hot water or even your own mouth.

Compare your results, in what conditions did the chocolate melt? You might also like to record the temperatures of the locations you used using a thermometer. Thus you can find out the exact temperature at which the chocolate melts.

What’s happening

At a certain temperature, your chocolate pieces undergo a physical change, from a solid to a liquid (or somewhere in between). On a hot day, sunlight is usually enough to melt chocolate, something you might have unfortunately already experienced. You can also reverse the process by putting the melted chocolate into a fridge or freezer, where it will go from a liquid back to a solid. The chocolate probably melted quite fast if you tried putting a piece in your mouth. What does this tell you about the temperature of your body? For further testing and experiments, you could compare white chocolate and dark chocolate. Do they melt at the same temperature? How about putting a sheet of aluminium foil between a paper plate and a piece of chocolate in the sun, what happens then?

EXP-3

Mixing Oil & Water

Some things just don’t get along well with each other. Take oil and water as an example; you can mix them together and shake as hard as you like, but they’ll never become friends.….or will they? Take this fun experiment a step further and find out how bringing oil and water together can help you wash your dishes and keep them sparkling clean.

What you need

Small soft drink bottle, Water, Food colouring, 2 tablespoons of cooking oil and Dish washing liquid or detergent.

What to do

Add a few drops of food colouring to the water.

Pour about 2 tablespoons of the coloured water along with the 2 tablespoons of cooking oil into the small soft drink bottle.

Screw the lid of the bottle tightly and shake the bottle as hard as you can.

Put the bottle back down and have a look, it may have seemed as though the liquids were mixing together but the oil will float back to the