Envis Centre, Ministry of Environment & Forest, Govt. of India

Printed Date: Sunday, September 20, 2020

Learning Lesson



Home Made Thermometer


What You Need



Rubbing alcohol

11-ounce clear, narrow-necked plastic bottle

Red food colouring

Clear plastic drinking straw

Modelling clay

Store bought thermometer (optional)


What You Do


Add equal parts tap water and rubbing alcohol to the bottle, filling it about a quarter of the way up.

Add a couple drops of red food colouring and mix by shaking the bottle.

Put the straw in the bottle, making sure it doesn't touch the bottom.

Use the modelling clay to seal the straw in place. Leave a portion of the straw sticking out from the bottle, making sure the clay forms a tight seal around the straw and over the bottle mouth, but don't close off the straw's opening.

To test if the homemade thermometer works, have your child place his hands around the bottle and observe what happens to the mixture.

Other ways to test the thermometer include placing it in a windowsill and observing how it reacts to the heat or cold there, or placing the thermometer in a bowl of hot water (always be careful!), followed up by placing the bottle into the refrigerator and the freezer.


What's Going On?


Just like any thermometer, the mixture expands when it's heated. As the alcohol-water mixture expands it moves up through the straw. If the bottle were to get very hot, the liquid would come through the top of the straw. As an extension, mark a scale for the thermometer; you'll need a real thermometer. Have your child place his homemade thermometer in one area and use the store-bought thermometer to identify the exact temperature. Mark the line of the liquid on the bottle and write its value. Then, encourage your kid to find other areas of varying warmth or coolness to create a temperature range for the thermometer.



Clean Water Using the Sun


What You Need


A wide plastic basin

A smaller jar or glass for collecting the clean water

A large piece of transparent plastic—plastic wrap works

String or rubber band to hold plastic in place




What You Do


Mix salt into some tap water and put the salty water in the bottom of your basin.

Place your collecting jar in the middle of your basin. Make sure the water is below the height of your collecting jar.

Cover the basin with the plastic wrap. Make sure that it's secured tightly at the edges. Use a string or rubber band to seal off the edges.

Place a stone in the middle of the plastic wrap just above your collecting jar.

Carefully move your solar still into the sun and let it sit for about half and hour.

After the solar still has been out in the sun for a while, return to it and encourage your child to record his observations.

After a few hours, when you take your solar still apart, taste the water in the collecting jar. What happened? Did you notice drops of water appearing on the inside of the plastic? Where did they come from?

Try to think about and describe the two changes of state that have occurred to the water retained in the collecting jar.


What Happened?


When water evaporates it leaves all of its impurities behind. If there are any bacteria or dissolved salts, they are left behind in the basin. Only pure water evaporates and is condensed on the plastic. That's why the water in the collecting jar is not salty.



How Do Oil Spills Harm Wildlife?


What You Need:

          Liquid soap



          ►Corn oil


          ►Vegetable oil



What You Do? 

Encourage your child to make a chart titled "Absorbed," "Repelled," and "Changes" across the top.

Ask him to also write "Water," "Oil," and "Liquid Soap" along the left side. Draw lines to make a grid.

Give your child the feather to examine. Ask him to look closely at the feather. What is its structure?

Have him dip the feather in the water. He should record whether the feather absorbed or repelled the water.

Instruct your child to dip the feather in the oil. Ask him to again record whether the feather absorbed or repelled the oil. Did anything else unusual happen to the feather?

Sprinkle water on the oil-soaked feather. Does the feather absorb or repel the water this time?

Invite your child to place some water in the bowl and add the liquid soap.

Try to remove the oil with the soapy water and the toothbrush.

What were the results? When he added oil, the feather should have drooped, and lost its ability to repel water.

Ask your child how well he was able to clean the feather. Did it return to its original condition?


What's Going On?

Feathers are constructed of strands of hair and miniature "hooks." This construction keeps the feathers close to the body, and maintains warmth and dryness. Oil compromises this ability, and endangers the bird's life.

The type of oil carried by tankers is much harder to remove from birds' feathers, although it is important to try! The best course of ending this tragic circumstance is to try and prevent oil spills altogether.



Compost Pit

Objective: To make use of biodegradable waste.


1. A spade for digging.
2. Dry grass or straw.


a. Dig a pit in the corner of your garden.
b. Line it with dry grass or straw.
c. Put in all biodegradable waste such as leftover foodstuff, vegetable peels, paper, dried leaves, etc.
d. Cover with a thin layer of soil.
e. Water once or twice a week to keep it moist.
f. Every 15 days or so turn the contents of the pit. Add more waste as it is generated.
g. After 3 or 4 months the compost manure will be ready for use.



Objective: Use of biodegradable waste.


1. A spade
2. Worms
3. Dry grass or straw.


a. The procedure is very similar to the compost pit, only in this case worms are added to the pit.
b. This form of composting is considered better as the worms feed on the waste and their excreta is mixed with it making it more fertile.


To build a bird bath


1. Three sturdy sticks;
2. An old tub, broad bowl, or any broad shallow dish. 
3. water


a. Put the three sticks on the ground as shown in the diagram.
b. Place the bowl on top and fill it with water. Now from a reasonable distance watch the birds having a bath.


Neighbourhood tree watch club

Objective: To learn to care for trees


a. Gather a group of friends and others who would be interested.
b. Form a club to take care of the trees in your neighborhood.
c. Count the number of trees in your area, each of you can adopt a few trees.
d. See that they are tended to, plant new trees where there are gaps or places where they are needed, water them and take care of them.
e. Hold regular meetings, involve your parents in the movement, and watch your neighborhood look healthy and green.


Rough recycled handmade paper

Objective: Recycling of waste paper.


1. Waste paper from old notebooks/old newspaper/old magazines. 
2. A little starch.
3. A bucket or an old basin.
4. A mortar and pestle or any other device to pound the paper.
5. A wire mesh sieve or a perforated plate.


a. Tear the paper you are using into small pieces.
b. Soak in warm water in a bucket for a little while with a little starch.
c. After a few hours take it out of the water and pound it with the mortar and pestle till it becomes soft and pulpy. Add more starch to it to thicken it.
d. Put this pulp in the sieve to allow the water to drip out. Press it if required to get the excess water out.
e. Now turn the sieve slowly upside down over a smooth surface and put some weight on it.
f. Once it dries up your handmade paper is ready for use. You will not be able to write on it but you can draw on it or use it for some other purpose.