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Topic 1. Water – Nature's Magician
Chapter 1A: Water – Visible and Invisible
To the teacher
Purpose
To provide information about the properties of water and the importance of water to life, and to focus on water being around for over 4 billion years.
Subject areas
History, Science, Language Arts, Math
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Note: It is important for students to know about the different properties of water so that they can have a better idea of the forms water takes as it moves around in the hydrologic cycle.
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Procedure
- Generate a class discussion with the following topics or ideas:
- Introduce the concept that water is a magical substance by discussing some of the different properties of water. For example, ask students how water is different in winter and in summer (ice, snow, sleet as opposed to warm rains and water for swimming); encourage them to talk about where they see examples of water vapour such as steam rising from boiling kettles or condensation forming on the outsides of glasses containing cold drinks.
- Depending on the grade level of the students, you might want to introduce more complex concepts, for example:
- Pure water at sea level boils at 100°C and freezes at 0°C. Point out that if a substance such as salt is dissolved in water, then the freezing point is lowered – that is why we spread salt on streets in winter to prevent ice formation.
- Water is a good cooling and heating agent. If students live near water they can feel how water absorbs the heat of the day and cools the surrounding air. More mature students could be asked to research land and sea breezes.
- Demonstrate to students (or assign as an activity to more mature students) that water is really molecules in motion. Introduce the phrase "capillary action" and show how water moves up the stalks of plants by using celery and coloured water. Point out that in the same way, blood, which is mostly water, moves through the smallest blood vessels, called "capillaries."
- Ask how long they think a person can live without water. (About three days.)
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Vocabulary
- atom
- atmosphere
- dissolve
- hydrogen
- molecules
- nutrients
- oxygen
- renewable
- solvent
- vapour
- vital
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References
Student information
 Picture this. Friday night has arrived. You're going out for the evening. You dash home after basketball practice, grab the shampoo, leap into the shower, turn on the taps, and nothing happens! One single solitary drip of water clings stubbornly to the shower head. And that's all there is.
Hello? Your father has managed to save a small bucketful of water and you can have your share? Big deal. One litre. How are you going to wash the grease from your hair, sweat from your body, and fuzz from your teeth? Not a pretty picture, is it?
Let's not take water for granted
 The title of this material asks us not to take water for granted. Do you? Do you ever think about the importance of water? All the different forms it comes in? All the different ways we use it?
We all know that water is the stuff we let flow down the bathroom drain while we hang around brushing our teeth. But it also comes in the form of ice, snow, vapour, and sleet.
The truth is, most of us don't think too much about water. We just use it, and in some cases we waste it.
Take a minute to think about all the ways you have used water in the past twenty-four hours. After you have made your mental list, ask yourself if there is another substance you can think of which you use the way you use water. What else can you drink, swim in, skate on, make snowballs with, and wash with, among other things?
Water as a solvent
An interesting fact about water is it can dissolve so many other substances. You probably dissolve substances in water every day without thinking about it. For example, when you stir sugar into a drink, or salt into your soup, you are using water as a solvent; and at school you use water to mix powdered paints to make different colours for art classes.
Because water is such a good solvent, it can dissolve nutrients and transfer them as vital food for plants and animals.
But, dissolved substances in water aren't always good. A drop of rain falling through the air dissolves atmospheric gases, and when these fall to the earth they can affect the land, lakes, and rivers. In another chapter we will look more closely at how dissolved acids in rain are transferred through the atmosphere and dropped on our lands, lakes, and rivers.
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Water facts
- 70% of your body is made of water
- pure water has no taste, no colour, and no smell
- water has a chemical name, H2O – this means it is made up of molecules containing two atoms of hydrogen and one atom of oxygen
- blood is 83% water
- water turns to ice at 0°C and to vapour at 100°C
- all living things, from the tiniest insect to the tallest tree, need water to survive
- more than half of the world's animal and plant species live in the water
- water is a good solvent – it can dissolve many substances
- most of our food is water, for example:
- tomatoes (95%)
- spinach (91%)
- milk (90%)
- apples (85%)
- hot dogs (56%)
- beef (61%)
- potatoes (88%)
- Canada has about 7% of the world's renewable freshwater supply
- water vapour forms a kind of "global blanket" which helps to keep the earth warm
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Where did all of our water come from?
That is a difficult question to answer, although scientists say that water has been here since the planet Earth was formed over 4 billion years ago.
The big bang theory about the forming of our planet states that water was created when hot gases from inside the earth erupted through volcanoes and geysers, and then cooled as the earth cooled. The gases then condensed to form a liquid which we call water. The amount of water formed then is the same amount we have today.
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Did you know?
Today 71% of the earth's surface is covered by salty oceans averaging 3.7 km deep. All five oceans are connected. Can you name them?
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Learning activities
Activity 1 – Math
Look back at your Student Information sheets. Based on the information in "Water Facts," calculate the following:
- You are making fresh tomato sauce and you have brought in 3 kilograms of tomatoes from the backyard. How much water is in these tomatoes?
- i) Weigh yourself. How much do you weigh? How much of you is water? If all the water were taken from you, how much would you weigh?
ii) Combine your weight with the weight of two other friends. How much of all three of you is water? (How much of an ordinary bathtub would this water fill?)
- In order to get dessert, you have to eat 600 grams of spinach. How much of this is water? Does this make you feel any better about eating spinach?
- How much water are you getting in a beef steak which weighs 500 grams?
- Make up two questions for a friend based on "Water Facts."
Activity 2 – History, Language Arts
Use a time line to show how long water molecules have been around and what important happenings they might have witnessed. (In the interest of saving paper and trees, limit the important events to the past 2000 years.)
OR
Use a water molecule to tell a story or relate a historical fact about your favourite period in history. If you could go back in time, what time would you go back to?
- when knights were around
- when dinosaurs roamed the earth
- when explorers came to Canada
- when your grandparents were children
Choose any time that interests you.
Remember, as a water molecule you can go anywhere – in the air, in water, underground, in any city or country in the world – and you can give a water-bird's eye-view of what really happened. So, make sure you point out how you (a young water molecule) were used back then.
Activity 3 – Science
 Water is the world's greatest solvent. Demonstrate to your class how water dissolves substances that other liquids will not.
- Take a small glass jar and fill it half with cooking oil and half with water. Add one drop of food colouring. Describe what happens.
- Water dissolves many substances. This can be good for us and it can be bad for us. Explain.
Activity 4 – Math and Science
Discover for yourself how much water is in an apple (or any fruit/vegetable).
If your teacher or librarian can help you with instructions, use this exercise to make the head of an apple doll.
 Peel an apple. Weigh it. For this you will need a set of scales or weights. Record the weight of the apple.
- Put the apple in a dry place for twelve or fourteen days and wait. Keep an eye on it and you will see it begin to shrivel up.
- At the end of this time, weigh the apple again. What is the difference in weight? What percentage of its weight has disappeared? Where did it go?
- Did your experiment with the apple support the information about most of our food being water?
- Try the same experiment with another fruit or vegetable, for example, a zucchini. Compare the percentage of weight lost with the apple's loss.
- What is the main conclusion you would draw from this experiment? Write your conclusion down.
Do a reverse of this experiment:
- Take some fruits or vegetables that have already been dried, for example, apricots, prunes, apples, or raisins.
- Weigh them and record the weights. Soak them in water.
- Note the changes. What happens? How long does this take? What is the difference in weight?
- Research: Why are some fruits dried? Who uses them this way? What other foods are dried?
Activity 5 – Science
Find out how much water is in a citrus fruit like an orange, lemon, or lime, and make a "pomander" as well.
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Note: A pomander is a ball of mixed fragrant substances sometimes used in a closet or cupboard.
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- Weigh the citrus fruit.
- Take a ribbon and tie it around the fruit. (You can hang the pomander from this later.)
- Press cloves into the skin of the fruit about one clove head apart.
- When the fruit is covered with cloves, wrap it in tissue paper and put it aside for five or six weeks.
- At the end of this time, take the fruit out and weigh it. Record the weight and compare it with the original weight. How much weight has been lost? What percentage of the original weight is this?
- Now that your experiment is finished, you have a gift for your mother or father to hang up in a closet or cupboard.
Activity 6 – Research, Science
Check your home or your school. Does either place have a humidifier or a dehumidifier? If not, do research in your library to find out about these appliances. Prepare answers to the following:
- What is the purpose of each?
- Are there times of the year when the amount of water is more? Less? Why do you think this is so?
- Explain in detail how either works. Prepare an illustration to present your information clearly.
- Try to conduct a "hands-on" experiment to find out how much water passes through either appliance in a day or a week.
Activity 7 – Science
This is your chance to show that different temperatures allow water to exist as a solid (ice), a liquid, and a gas (or vapour).
Ask your teacher for help (or if you are working at home, ask your parents).
 You will need:
- an electric kettle
- water
- a cookie sheet (with sides)
- ice cubes
- kitchen mitts
What to do:
- boil water in an electric kettle
- using kitchen mitts, hold the cookie sheet full of ice cubes over the steam from the spout
What did you see? Answer the following questions:
- What happened to the water which boiled? (This is called evaporation. How would you describe evaporation?)
- What happened to the ice?
- What happened to the outside of the pan which contained the ice? (This is called condensation. How would you describe condensation?)
- Would the same process have occurred if the water had not been heated?
- What would happen if you placed the pan of water in the freezer?
Write a conclusion explaining how different temperatures affect the different forms of water.
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