Make dirty water clean - How to filter drinking water

Most young children have not given too much thought to clean water. They turn on the tap and clean, ready to drink water comes out. Some are used to drinking water out of a water filter system.

This nature education experiment shows children how dirty muddy water can be cleaned by filtering it through gravel and sand and shows them what goes on inside a water filtering system.

You will need:

• sand
• blotting paper or 3 or 4 coffee filters
• clean flower pot
• transparent jug
• large measuring cup or pouring jug
• Scissors
• Tablecloth or dish towel
• Gravel
• Cotton wool
• Dirty water (you can make tap water dirty by adding food colouring, cooking oil, small bits of plastic or soil)
• Glass

Have small groups of children take turns making a water filter (or if necessary the class can sit in a circle and watch as you do it)

• Put blotting paper or 3 or 4 coffee filters, then sand, and finally gravel in a clean flower pot
• Place the flower pot in a larger transparent container so the filtered water can drip through and the children can observe it
• In a large measuring cup, place dirt, bits of plant matter and water
• Mix it up to make muddy water
• Pour the muddy water into the flower pot as shown in the image on the right.
• Children observe the color of the water dripping out the bottom of the pot into the transparent container
• Ask questions - Where did the dirt go? Why did cleaner water come out?
• Take the filter apart and try and find the dirt and bits of plant matter

What's happening?

Your filter gets rid of solid large particles that are not dissolved in the dirty water. The size of the particles that can be removed by filtration depends on the size of the filter you use.

A filter with small holes will stop more particles getting through than a filter with large holes.

Your filter won't get rid of food colouring, because food colouring is dissolved in the water. A technique called distillation is used in laboratories to get rid of substances dissolved in water.

The water you drink from taps is cleaned by lots of processes. Filtration is just the start. The water is also disinfected to get rid of microbes.

More: Try arranging the layers in a different order and compare the color of the filtered water.

How density works and How you can change the density of a liquid using by SALT WATER EGG EXPERIMENT

Have you ever tried swimming in the sea? Did you notice that you could float more easily in the open waters than when you’re swimming in fresh water or even in a swimming pool? This experiment will help you understand why!

 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 fun facts about density.


  Objective: To understand how density works and how you can change the density of a liquid.


 


Materials Needed:

• Cups 
• Eggs 
• Salt

 

Step 1) Fill 3 glasses with 250ml of water and place a fresh egg in one of the glasses, watch as it sinks.


Step 2) Put 4 tsp of salt into one of the glasses stir it up and place an egg in the water. Watch as it floats.

StStep 3) Put 4 tsp of salt into the final glass stir it up and pour out some of the salt water. Now place an egg in the water. Slowly and carefully pour fresh water into the glass of salt water and watch as the egg sinks down till the middle.

 HOW IT WORKS:

Density is the amount of space something takes up per volume and when you add more mass to the same amount of space being taken up you can change the density of a liquid. When you drop a raw egg into fresh water the egg doesnt displace enough water making the egg more dence then the water around it. Creating an unbalanced force which sends the egg to the bottom of its container. When you add 4 tsp of salt to 250 ml of water and stir, the salt crystals break down into molecules and and fill in the holes inbetween the water molecules. The solution now has more mass in the same space or volume, which changes the density of the water. When you add the egg to the salt water you displace the same amount of water but that space has more molecules in it and the egg becomes less dence then the salt water around it. When you slowly add fresh water to salt water the less dence fresh water floats on top of the more dence salt water and you create a dencity colum of water. The egg sinks through the less dence fresh water and floats on the more dence salt water. To make anything that doesnt float, such as a bowling ball that doesnt float, you just have to increase or lower the density of the liquid you want the object to float in.

  FLOAT AN EGG IN THE MIDDLE OF WATER!! (DENSITY COLUME) SCIENCE EXPERIMENT "

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