Assignment #3: Lava Lite!!

Transcription

1 Assignment #3: Lava Lite!! This activity entails making a lava lamp. PROCEDURE: GOALS: 1) Fill a glass cup with three inches of water. 2) Put about _ of an inch of oil in the water. Notice what the oil does. 3) Put some food coloring in the mixture. Observe. 4) Take a handful of salt and start pouring the salt on the mixture. Hold up to sufficient light and observe what you see. To measure proper quantities of substances. Hypothesis formulation Observation and Questioning Communication OBJECTIVES (KISS): Get used to using science equipment Describe observations to each step of experiment Follow instructions of procedure in order to be successful in the experiment Work well with others Formulate questions about possible outcomes Predict and test an outcome PRESCRIBED LEARNING OUTCOMES (TSWBAT): Grade 1: Communicate their observations, experiences and thinking in a variety of ways (verbally, pictorially and graphically) Grade 2: Use their senses to interpret their observations. Grade 3: Ask questions that foster investigations and explorations relevant to the content. PLAY-by-PLAY

2 Participants: (B) Bernadette, (A) Andrew, (J) Joanna (J) So this is probably a grade one to three experiment and it s a lava lamp. So, first the kids have to fill the glass with water and then they are going to put oil on top of it, then food coloring and then salt on top of the mixture and see what happens. (J) Ok you guys so take a glass and fill it with water to the line where it says. (B) To the bottom? (J) To the line where it says water. (B) Ok (J) Got it? (B) Yep (J) Ok, now put some oil into it, a good saturation Ok, look at where the oil goes you guys. Where does it go? (B) Straight to the top. (A) It s floating. (J) Ok so now get some food coloring and dump some food coloring in there. Make it look pretty. Careful not to get it all over yourself. (B) Much more? Should I mix it? (J) Yeah, make it so you can really see it. Put lots in. You ve got lots of oil in there Bern. (B) Well you told me Oh, you did a good squirting job! (J) Andrew, you don t have much oil compared to Bern (B) Well he has more water doesn t he? (J) Yep. K, now take the salt and take some in your hand. Now, I m going to count to five and as I m counting put the salt in. (B) Like a pinch?

3 (J) Yeah like a pinch. Go slow and see what happens and then go faster. One..two.. (B) It s dropping! Look! (A) Laughs. (B) It s like falling apart. (J) Can you hold that up to the light Bern? (B) Yep. See it s falling or it was falling (J) Can you hold it closer Bern. Can you move so your hand s not in the way. (B) Well there s salt in my other hand. (J) Let s see Andrew. Ew, it looks kind of nasty. Yeah, keep putting salt in. (A) Check this out. See, there s a lot more. (J) Good I can see that really well. Ooh! Yeah! (B) Maybe the trick is to add more salt. (J) Yeah I think you need to add more Bern. ((B) Oh cool! Look at that one!! That s totally a lava lamp! I ll just dump in a whole bunch. HAHA! Look at that goop! (J) It s sitting on the surface. (B) There s like two layers. The clear layer and the colored layer. (A) what happens if we stir it up? (B) I don t think we should stir it up. (J) Maybe it ll happen all over again. (B) Well, mine was, it was going up then down again. I shouldn t have powered the drops in. It s better to be clear. (J) Powered the drops in?

4 (B) well yeah, you know how at first I had drops in. Now it s all red but I should have left the red drops so it could be seen easier. See that red drop? (J) Can you hold it up to the light? (B) I think it stopped. (J) What happens if you add a bit more salt? (B) Probably don t need to add more salt. (J) How do lava lamps keep working then, cause you don t always add salt. (B) Jiggle it. Oops I don t think that really helps. Jiggling doesn t really help. Lava lamps are heated though. (J) Oh, if you heated it. Right (A) Heat changes the density and makes it lighter. (B) Yeah, what does the salt do to the water? It makes it slightly hotter right? Or slightly colder? (J) Hotter. (B) Hotter. So it s like we re heating it. Bernie proceeds to add way more salt. Laughter INTERPRETATION OF THEIR THINKING AND UNDERSTANDING (1) The thinker: Bernadette was constantly wondering what was going on. She watched what Andrew did and wondered why hers acted the way it did if she tried something a certain way. She first added a very small amount of salt and coloring props. After watching how much food coloring he put in (and I suggested it would be easier to see) she then put more in. She was wondering what it was the salt was doing that caused this effect like a lava lamp. She then wondered if the salt made the solution warmer. She wondered at the end if she should

5 have left the small amount of food coloring in the mix and not mixed it. Would it have been easier to see the drops? (2) The innovator Andrew was quiet for most of the experiment. He added first a bit of salt and then wondered what would happen if he added a whole bunch. Then he tried mixing it. After Bernadette mentioned the warmth the salt was adding, he made the connection to the lava lamp that it would need to be heated which changes the density of the wax in it which causes it to rise, same as what the salt did to the oilattached to the oil and dropped because it has a higher density than water. Once it hit the bottom though, the oil would eventually get away and if it was heated this would happen faster and it would rise again to the top. PERSONAL REFLECTIONS: My role was successful in giving instructions. In a real situation I would probably have to be more specific with amounts. This way, the kids put in as much salt and oil as they thought was the right amount, which was fine. I chose this activity for simplicity purposes. I like the fact that science can be shown in quick ways and that ingredients do not have to be expensive all the time. Little lessons are not as daunting and the children would enjoy them as well. It was successful in that it worked the first time. With children this may not be so, but I think it was quite reasonable for primary years. I think I could use this activity again and I could bring in a real lava lamp for them to see first in case they were not familiar, and also bring in more colors and try mixing. After they were finished they could draw pictures of their observations, perhaps showing the different layers of the substances. This is a good activity for showing density. First salt, then water, and finally oil in highest to lowest density order. This experiment could be done before the coke can experiment (diet versus regular) and see if the kids could get the explanation of why the regular can sinks. I also wonder what would happen if the lava mixture was heated, whether the salt would combine with the oil and sink to the bottom again. That could possibly be used as an extension of the activity. What is going on here? (Muller, Teacher-in-residence) Lava Lites are lamps that were invented by an English man named Craven Walker in They are basically tall thin glass jars filled with liquid and a special kind of colored wax, set on top of a base with a light bulb. When the bulb is turned on, the lamp glows, the liquid heats up, and the wax begins to melt. Blobs of wax rise to the top of the lamp, then cool and sink back down--over and over again.

6 Oil floats on water because a drop of oil is lighter than a drop of water the same size. Another way of saying this is to say that water is denser than oil. Density is a measurement of how much a given volume of something weighs. Things that are less dense than water will float in water. Things that are more dense than water will sink. Even though oil and water are both liquids, they are what chemists call immiscible liquids. That's a fancy word that means they don't mix. What happens when I pour salt on the oil? Salt is heavier than water, so when you pour salt on the oil, it sinks to the bottom of the mixture, carrying a blob of oil with it. In the water, the salt starts to dissolve. As it dissolves, the salt releases the oil, which floats back up to the top of the water. This looks like a Lava Lite. How does a Lava Lite work? Like your oil and water, the "lava" in a Lava Lite doesn't mix with the liquid that surrounds it. When it's cool, the "lava" is a little bit denser than the liquid surrounding it. When the "lava" rests on the bottom of the Lava Lite, the light bulb in the lamp warms it up. As it warms up, the "lava" expands a little. When it expands, the "lava" stays the same weight but it takes up more space-so it's less dense. When it's warm enough, the "lava" is less dense than the surrounding liquid, and so it rises up to the top to float. At the top of the lamp, it cools down, becomes more dense, and sinks once again. This cycle repeats over and over as the "lava" warms up and rises, then cools down and sinks. Where did this experiment come from, anyway? Exploratorium Teacher-in-Residence Eric Muller created this activity while playing with his food in a Chinese restaurant.

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