Activity: Explore physical properties of water and human-water interactions
Level: Grade 5-6
Time: 2 hours
After successfully completing this activity, the student will be able to:
Water temperature and oxygen
What dissolves in water?
Acids and bases
Author: Rebecca Burton, feel free to email questions and comments from you and your students. Creation and maintenance of this web site was made possible by NSF-ILI Grant DUE 9750658.
The National Science Foundation has recommended that students in grades 5-8 become involved in partial and complete inquiry activities. This activity allows students to explore some of the chemical properties of water and also the interactions between humans and their water supply.
Activity: Oxygen and water temperature, hypothesis testing
The following outline is provided as a source of ideas. It is not intended as a script.
What sort of questions can science answer? What can't it answer?
What steps do we need to answer a question scientifically?
If we ask the question whether water holds more oxygen at some temperatures than at others, how can we answer it?
What are the 3 hypotheses (guesses)?
When we try to force more air into the water than it can hold, what happens?
[Demonstrate- Use straw or squeeze bottle, make bubbles]
If the hypothesis is true, what should we see? Make predictions for each.
If warm water holds more, what should happen as it cools off? [oxygen leaves]
Can we see the oxygen as it comes out of the water?
If cold water holds more, what should happen when the cold water warms up?
[List hypotheses and predictions in table form, which one will have bubbles?]
|Temperature doesn't effect||All vials same|
|Warm holds more||More bubbles in water starting out hot|
|Cold holds more||More bubbles in water starting out cold|
Put hot, cold, and room temperature water in 3 separate vials. Why use equal volumes?
Measure starting temperature and write it on the inside of the cap. Why the inside?
Tap vials and tilt to remove visible bubbles from all.
Rearrange vials to hide their identity. Have one person label the tops of the vials with a 1, 2, or 3.
Set aside for later examination and discussion.
Discussion-The water cycle
How do we use water? [drinking, washing, flushing, cooking, recreation, irrigation, fighting fires, cooling engines, etc.]
How much do we use per day? [500 l/125 gal]
How much is used for you (farming, manufacturing)? [7200 l/1800 gal]
Where does water come from and where does it go when we've used it?
[Draw water cycle showing precipitation, flow, condensation, evaporation]
How much rainfall do we get in a year here? [average and variation]
Find your local data here
Where does our local water come from? [lake, aquifer, river, reservior?]
Where does our local water go? [treatment plants, aquifer, ocean, atmosphere]
What is carried in water as it flows to the sea?
Which substances will dissolve in water? [make hypotheses]
Activity - What dissolves in water?
Lab Safety - Keep stuff away from eyes and mouth, use things only as directed, ask if you're unsure.
Put some of test substance [soil, sand, aquarium gravel, oil, acid (vinegar), etc.] in bottle with water.
Label the bottle.
Shake it up.
Discussion-What is carried by runoff and why is that important?
What dissolved and what didn't?
What floated ? Why?
Are things settling out now? Why?
Which settled out faster, "fine" particles or big ones?
Were your hypotheses supported or refuted?
What is runoff?
What else would water pick up? [sewage, "germs", large objects, animals and plants]
Where will these things end up?
What happens when a lot of rain falls in a short time?
Will more things be picked up?
Streams can be constant or "flashy".
Which is ours? Does this mean more stuff in runoff?
What effects can runoff have?
Dirt [clogs gills and reduces light for plants, channel erosion]
Oil [clogs gills, mats fur and feathers, blocks surface, hurts eyes, etc.]
What happens when it reaches the sea? [relative density, dilution]
Acids and bases
Discussion - Acidic things and bitter things
Name some sour things. Name some bitter-tasting things.
[Draw- pH scale with examples battery acid, stomach acid, oven cleaner, ammonia, etc.
pH and stream quality, Explanation of pH for kids, pH scale]
Which things are dangerous? Which things are neutral?
Activity - What is acidic and what is basic?
Lab safety - Keep stuff away from eyes and mouth, use things only as directed, ask if you're unsure. Don't taste anything!
Test a substance by dipping a test strip in the labeled vial. [detergent, lemon juice,
soap, cola, fertilizer, vinegar, tap water, distilled water, etc. Obviously, some items on the scale are too dangerous to bring into the classroom]
Compare it with the color chart on the package.
Write the substance and its pH on the strip. Tape it to the scale used for discussion earlier.
Discussion-Acids and bases in our water
Where did things fall on the scale?
Which things could end up in our streams and ocean?
How would this affect our water?
How would it affect plants and animals?
Can rain pick up things on its way to the ground? [dust, acid, "smog"]
Smog can produce acid rain. How would this affect runoff and the life in the stream and sea?
How much water do you have to add to raise pH of an acid by one step? [Each "step" multiplies by 10. This may be a good time to talk about logs.]
Discussion - Temperature and water
What's your body temperature?
How do you control it?
How do plants and fish control theirs?
[Draw- F and C temperature scale showing boiling and freezing point for water, range for oceans, life processes range, human body temperature]
Which varies more, land or water temperature?
What temperature is the water around here? [discuss mean and variation]
Does the stream's temperature matter?
Activity-Water temperature and oxygen content
[Review hypotheses and predictions]
Look at vials filled earlier.
Which has the most bubbles? Why? [Go back to earlier predictions and evaluate them]
If cold water holds more oxygen, what does this mean to fish?
What things affect stream water temperature?
Summarize how humans depend on water and how we can affect it.
Possible Assessment Criteria
In future class periods, you might wish to discuss any of the following topics:
Last update: 12/13/02 by Rebecca Burton, Dept. of Biology, Alverno College