2. Check & Reflect Answers
P. 346
1. You should not drink water from a stream even if you know it’s not contaminated by human activities. It may have naturally occuring organisms that are harmful.
2. Water supplies come from melting water or rainwater depending on the season. The amount of silt and contaminants in water may vary with the amount of flow in the stream. (ex. After severe storms, the flow may increase and water may be contaminated, or in the spring meltwater can bring large amounts of organic material from rotting leaves that had trapped ice)

3. AYL Answers
P. 347
1. Potable water is water that is safe to drink. Out of a sample of 1000L representing the world’s water supply of fresh water, only 0.03 L is potable.
3. Chlorine is added to our water supplies to kill organisms that might make people sick, such as bacteria or protozoa
4. Water is described as being ‘hard’ when it contains dissolved calcium and magnesium. Soft water is water that has little calcium and magnesium.

4. Backpackers often carry a water pump
Backpackers often carry a water pump. These pumps have replaceable filters that can remove silt and bacteria from water.From the description and photo, we can infer that these pumps use _______ to remove silt from water.
A) reverse osmosis
B) evaporation
C) Chemical treatment
D) Coal filters

5. A- Reverse Osmosis
Reverse osmosis is the process of forcing water though a filter containing a series of partially permeable membranes. (With each consecutive membrane allowing only the next smallest particle of debris to pass.) In a good quality filter, the smallest filter has holes so small that not even bacteria can pass. This filters out all of the debris and bacteria, but will still not clean water that is polluted with liquid pollutants or dissolved toxins. For example, even the best backpacking water pump will not filter out mercury.

6. Why is untreated water unsafe?
A) bacteria B) mineral pollutants C) industrial pollutants D) all of the above

7. In recent years, it has been said that "our water is tainted with antibiotics". This is because people who live further upstream have put their no longer needed prescriptions down the drain. It is a concern that healthy people might be taking in even minute quantities of these medicines or affecting the wildlife. How could these antibiotics be otherwise disposed of?
A) unlined landfills B) into storm sewers C) down the toilet D) collection bins at pharmacies

8. 2.1 Waves & Tides
Three peanuts were walking in a park and one got a salted.

9. Review to this point…
Water exists in many forms such as all 3 states (gas, liquid, & solid).
Water can be found everywhere (underground, surface, & air).
Water affects both biotic and abiotic factors.
Water affects both the weather and climate around the world.

10. Waves & Tides Waves and tides are two ways in which water moves.
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Waves and tides are two ways in which water moves.
Waves are movements on the surface.
All bodies of water, even small puddles, have waves
Tides are regular rising and falling of very large bodies of water.
(tides also happen in lakes & rivers, but they’re so small, we can’t see them!)

11. Demo!
Making Waves
Materials: A pan, water, and a cork
(ex. P. 350).

12. Parts of a Wave

14. The Movement of Water Waves
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The Movement of Water Waves
Waves
Recall waves are a form of energy
Waves begin from a disturbance
in water, circular movement of water particles that cause a change in pattern that moves along the water’s surface; the pattern can move over long distances but the water particles do not.
(don’t copy: analogy- pounding your fist on a table, or a rope tied to a door)

15. Wave Animation

16. Cause of Water Waves
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Most waves are caused by the combination of a local sea and swells.
Local seas are made by the wind :
Wind speed increases
Distance the wind blows over the water (called fetch)
Time wind has blown over fetch
Swells move away from local seas where they were produced (and continue without wind)
In the open water the waves appear to move up and down.

17. Copy this down!
Why do Water Waves Buckle and Crash?
When the wave reaches the shore it drags on the bottom of the ocean and slows down, which causes the top of the wave to rise up and crash down on the shore, which leads to most damage.

18. To Review

19. Surfing!
Is there more to than just riding a wave for a professional surfer?

20. Effects of Waves on Shorelines
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Effects of Waves on Shorelines
The force of waves can affect both a hard rock and soft sand shoreline.
Waves regularly cause erosion on land surfaces.

22. IB Criterion A Question:
What are the big problems with tubing on a lake? Explain!
- don’t forget to include how does this impact humans!

24. Tides Tide – daily changes in water level of the oceans.
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Tides
Tide – daily changes in water level of the oceans.
- Tidal changes are seen regularly along the coast.
- Most places there are 2 high tides and 2 low tides a day.

25. Tides High Tide – highest water level along the coast
Low Tide – lowest water level along the coast

26. The Bay of Fundy- Largest tides in the world!

27. Copy this down!
The Cause of Tides
Water is affected by forces in space because of centripetal force 
The main cause of tides is the gravitational force of the moon.
The sun also has an influence, but not as great
The side closest to the moon feels a strong pull from the moon creating a bulge.
The opposite side of the Earth also has a smaller bulge due to other forces.
(see pg 424 of Science in Action textbook)

28. The Causes of Tides The 2 bulges on both sides are the high tides.
As the Earth rotates the points of the high tides also change.
- The movements create 2 high tides and 2 low tides every 24 hours and 50 mins (called the lunar day).
Very similar to the 24 hour day (solar day).
People keep track of the tides with guides called tide tables.

31. What is a Rip Tides?

32. http://streaming. discoveryeducation. com/search/assetDetail. cfm

33. Homework!
Check & Reflect p. 354
1, 2, 4