Trolling for Misconceptions and the Limits of Understanding

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I have just begun the third (of eight) integrated science/history units for this 6th grade school year, entitled H2O: The Water We Drink. The unit will focus on several aspects of water: its physical & chemical properties; viewed with respect to the Earth system, as weather and the water cycle; and local issues here on the Dakar Peninsula, particularly with respect to conservation and water quality monitoring.

This blog entry highlights three opening activities in this unit: an audio-taped survey of students' prior knowledge; an assignment which asked students to capture their ideas about the structure of water; and their reflections about the need to assess students understanding prior to a unit such such as this.

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My students are not blank slates. Quite the opposite. They arrive with lots of ideas about how the world works, based upon years of experience, schooling, and a drive to make sense of it all. As you'll note below, many of their ideas are a repetition of things previously heard or taught, often fragments of concepts, names of things, combinations of ideas admixed with a tad of imagination.

These preconceptions, often misconceptions, tend to been firmly rooted and resilient to change, even with direct instruction. We must play detective, and suss out these ideas, make them visible, and confront the misconceptions directly.

This unit opened with a survey of the kids' prior knowledge/understanding. Sitting around a container of water, I asked them: what do you know about this stuff? The kids readily shared their thoughts about water, on topics ranging from perspiration, states of matter, density, buoyancy, the meaning of H2O, etc. Their responses were audio-taped, and a cross-section is offered below:

1. water doesn’t really have a shape, it depends on what’s around it, the container

2. when you sweat you loose the water from your muscles and begin to cramp, they don’t work as well

3. if you’re running you’re not loosing water, you’re loosing grease

4. the subatomic atoms, when water begins to freeze, the atoms start to change their shape, they keep the circle, but when they get hard, and then they change shape, it’s like a spear with triangles sticking out, and when it becomes a gas, it just becomes lighter, it doesn’t change shape

5. every thing growing needs water

If pour cold water into hot water, what will happen?

6. the cold water is heavier, or maybe it’s the opposite, one of the will go under, so there will be two different layers, the temperature makes one of them heavier, the cold water is heavier, something happens to the atoms

7. it depends on the temperature, the hot water will be less

why does ice float?

8. when things get frozen the molecules get bigger, it’s still the same weight, but because it gets bigger it’s more spread apart, so it’s lighter, only when water becomes ice, then the molecules gets large, that’s why when you take a water bottle and freeze it it might pop

9. atoms are mostly air, so I think it has something to do with, the middle of the atom, and sub-atomic particles going around the atom, the ones going around the middle of the atom, because of the temperature, they would probably not be able to go around the atoms, and so it would become hard like ice

10. (to clean water) you can freeze it, so the particles and living things die, then we can filter it, to take away all the dirt in it

11. I don’t think you sweat in water, even in hot water, your sweat would become hot too, if you’ve covered with water, you’re body wouldn’t do that, it’s impractical

12. since there are gases in water, they are also made up of molecules

13. if you don’t drink water, you’ll lose all of your blood, you need water to run the blood through your veins, blood is also made up of water

14. H is hydrogen, O is oxygen, and the 2 makes the water drinkable, because it would be dangerous because it’s explosive

15. the voice box needs water to produce sound

16. if you don’t have water on your body, you body will have a hard time functioning, you’ll be skinny, and you can die

17. the earth is made out of 75% water

18. when water becomes ice the particles freeze

19. when we’re running, your body gets tired, because there’s not a lot of water, we loose a lot of water, and when we drink and our body begins to work

20. if water never existed it would be hard to eat because much of the food nowadays is full of water, like carrots; water is used to make food; if we cook we have to use water

21. water goes in your veins, and moves blood smoothly, if not the blood will stay in one place, and if you don’t drink water for a day and a half you’ll die

22. water is made by thousands of microscopic organisms

23. water is made by forms of gases put together; the H is hydrogen, there’s oxide for the O, and there’s two, I’m not sure what that is, I think it’s either hydrogen twice, or oxide twice, but I’m not sure

24. when you drink water it’s sort of a way to make you feel more refreshed, and if you’re kind of just dry your organs or something can start going wrong

25. if he is used to the water (that he drinks) his body can easily protect him from sicknesses, but if I were to drink it the amount of organisms that are bad for me would be really bad, and my body wouldn’t be able to fight it, and I would get sick

26. here there is a lot of garbage around, so if it were to come from really far away mountains, because I don’t see any mountains that have snow, I don’t even know where it comes from here, but it would go through these tubes, but here I don’t think they clean it very often

27. I think that when the water comes to the tap, inside the tap there are germs everywhere, so when water comes to the tap it changes color

28. about 75% of the Earth is water, I think, so that makes water very essential, very important

29. when you go to a different country the water tastes different. Why?

30. I heard that there are two kinds of water: water that you can drink and water that you can’t drink. The water that you can’t drink is like the water from the sea

31. when you come to a new place the water is different and I think your blood cells are not used to it and after some time they find a way to stop this different thing in the water

32. when you taste different waters, it could be from the source, if you leave it in the bottle a lot, like plastic, sometimes it’s not good to drink, but you could be used to the taste of it, from a plastic bottle

33. the ice forms is when the molecules all get blocked together, they come together and freeze. (When we heat the ice) they come out, and they’re free then, because they have space, yeah, they come apart, because the heat makes them free, it melts and spreads out, and the molecules have more space

34. every time it changes state, from solid to liquid to gas, it wears out, some things get left behind

35. we can only drink one type of water, we can’t drink saltwater, or frozen water

36. I heard that it expanses, so when it changes to ice, it’s more than water

37. I’m not sure why it goes up (water vapor)

38. the hydrogen and oxide, when they come together, it’s pressure, there’s the pressure, when it hardens to ice it’s the pressure comes together and it expands, it doesn’t decrease, the pressure makes it expand, and it makes it hard, bigger not smaller

at what temperature does water boil?

39. 50 degrees C . . . 100 degrees C . . . 75 degrees C . . . 60 . . . 255 degrees Fahrenheit

what does boil mean?

40. to make it hot

41. it can be just 50 percent, like in the middle for normal

42. it makes zero for ice and 100 for boil

43. it’s kinda like . . . I’m not sure

44. it starts to steam a lot, and the water is less, the molecules feel light and evaporate

45. the heat makes the water to evaporate

46. the molecules as a gas get smaller, so they’re lighter

47. boil means when things get bubbly

48. the molecules get smaller, and just forms a bubble and pops

What is a molecule?

49. it’s like a little bubble

50. it’s when the water starts to shake, the fire’s so hot, the air can’t take it any more and it starts to shake, the air in the water’s hot, and it transforms into a bubble and pops

51. I think the water evaporates and is attracted to the cold surface (like the underside of a pot lid)

52. cold water will go down, it’s kinda heavier because it’s cold, the cold water it’s a bit together, it’s a bit squished, not a lot, then it goes down

53. when you boil water it splits into tiny pieces, into gas, and it gets smaller and smaller, and weighs less, it evaporates, then the water starts getting smaller and smaller at the top, then it goes down because it’s lighter, hot water will go down and cold water will come up

I followed up with clarifying questions, and probes aimed at determining the depth of their understanding (or the lack thereof). Most students had had little exposure to atomic theory (atoms & molecules) or heat transfer in their schooling.

Following this survey, I asked: what questions do you have about water that you'd like to answer over the course of this unit? Students wondered . . .

How do we separate water, the particles, hydrogen from oxygen?

How can we see the molecules in the water?

What really is water?

Why can’t we breathe under water like fish?

How do bubbles end up in the middle of an ice cube?

How do they make water, and what are the things they put in there?

At the beginning, where did water come from?

What is density? What makes something dense?

How do we clean water?

What do they put in the water, because in different countries the water tastes different?

Is our solar system formed like a molecule?

Why do we need water?

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Students were then assigned to pretend that they had an incredible shrinking submarine which would descend into a cup of water and shrink down to a size so small that they could observe the tiniest building blocks of water. They were to capture their observations in both words and pictures. The aim was to both to assess their understanding of atoms and molecules, and to create a point of reference against which we might gauge learning.

Pictures 2-8 above are a cross-section of the kids' ideas about the structure of water. About Picture2, L. writes:

I think water looks like small particles that can be attached together or not. Each one has four layers in them. The first layer is the one on the edge of the particle. It shows the color of the three different forms of the water -- ice cubes, liquid water, and the vaporation, which is what I wanted to show. The second layer is the one next to the first layer. It is there to make the taste of the three different forms of water. It also decides whether it tastes cold or hot. The third layer is there to protect the fourth layer. It protects it from the bacterial or things that are not clean. The fourth layer is the center. It's a heart. The heart makes everything work, just like ours.

In Picture3, S. explains:

It would be as if there were different forms in the shape of a puzzle all linked together with a series of strings. The strings symbolize that when water is frozen, water becomes denser and comes together, and that when water is boiling it spreads more apart. If the water is neither very hot nor very cold, the strings won't be as big or as small. The forms would have different colored bordering, each bordering signifies something. The outer border is hydrogen, the second border is oxide, and the center is "2". Hydrogen is white with dots in it because of the clearness of water, and the dots are dirt that has been collected inside of the water. Oxide is a greyish blue because as you get to the center of the shape the colors become darker. The very center is "2" because I heard a theory from my friend that without the hydrogen and oxide the "2" can make an explosion. So I figured it should be in the center so that before the "2" gets out it has mixed with the hydrogen and oxide and is no longer dangerous. That is what I think I would see if I shrunk to the size of a particle on an ant's leg and dove into a cup of water.

In Picture6, E. writes:

These different colored "creatures" are called molecules. Atoms are what make up everything in the world and molecules are a big group of atoms together. I am not sure these molecules are the same colors they are in the picture. These molecules are not swimming in water, but they are water, what the water is made of. The extra space in between are the atoms which are, as I said above, what makes up the earth. Some of this information is from a google and some I vaguely remember from 4th grade.