book collections email follower instructable user
Picture of Back to School Science Experiment
IMG_0953.JPG

I learned this trick at Happy Hour a few years back and have used it in my science class as an inquiry lab ever since. I just don't tell my students where I learned it!

This lab does require matches and involves fire so please use caution. Adult supervision is required!!

I suggest reading "Step One" before watching the video.

Step 1: "Water in the Glass"

This is the perfect science experiment to get kids thinking. I use this experiment to introduce the steps of the scientific method and to spark an interest in science related topics for my 7th graders. Because it's an inquiry lab, you might want to figure it out on your own. If so, do not watch the video or move on to the next step. If not, click through the steps or watch the video to learn a really neat trick. To understand the science behind the experiment, an explanation is on the final step and in the description below the video. You can also check out some of the brilliant comments by members of Instructables in the comments section!!

Here is how I pose the question to my students...

"How can I get the water from the plate back into the glass without lifting the plate?"

These are your materials:

A dinner plate, a drinking glass, water, a lime wedge, and 5 matches

Cool, will be great for school. thanks

DEEJAY6423 years ago

awesome im gonna do this right now

smashman3 years ago

great

I love it!! So creative
Festrada0073 years ago
If all of you would like to know where the water comes from, I woul suggest measuring the depth of the water in the platewith glass and fruit in the water. Then conduct the experiment and re mesure the water. The vacuum is created by the flame convering the oxygen into heat. You also notice how large forest fires creat their own wind by creating low pressure pockets in the heart of the fire. Simple thermodynamics. ;)
kenza30003 years ago

uhl.

CIMG1657.JPG
kenza30003 years ago

kerrren

TammyMoore4 years ago

I love the creativity used here lol should keep this article in mind.

stacko123454 years ago
Yeah going to show her the your 'ible maybe for a class experiment if that's ok with you
stacko123454 years ago

Will let us do it

Biodynamic (author)  stacko123454 years ago
Bring all the materials and see if your science teacher can figure it out. If not your science teacher, bring the materials to the teacher you think would find it awesome and see if they can do it, but I hope your science teacher would be interested enough by the challenge that they would use it as a teachable moment. Good luck. (Maybe have the teacher supply the matches ;)
stacko123454 years ago

Cool trick but I don't think our science teacher

Awsome trick
A trick that chlidren would love to peform??????
htariq54 years ago

I DID it i worked very well and i showed it to my class fellows and explained

Were you saying that the volume shrinks or the glass shrinks? the volume that the glass holds or the volume of the gas inside?
swawrzyniak4 years ago

I used to do this as a demo in my science class and I found I had to be careful about explanations. When using a candle, the flame does not go out when the oxygen is gone. I used to demo relighting the candle for a little while after waiting a minute (I started with a thin bare wire around the wick that I could short the wire and heat the wick with a power supply). Carbon dioxide and water are produced so it is not accurate to say the negative pressure inside is from using up the oxygen. The event also demo's that the water does not go in as the candle first burns. If anything, air bubbles move out of the glass until the candle burns out. Then as the gasses inside cool, you get the negative pressure inside compared to outside and then the water moves in. The used up oxygen point is easier to make by sticking some steel wool up in the glass with no heat source and waiting for most of the oxygen molecules to become part of the rust that forms. I was very lucky that my college science teaching methods class over 30 years ago focused on these kinds of experiences.

From one teacher to another, thanks for challenging students.

Biodynamic (author)  swawrzyniak4 years ago

I hate that I didn't explain it correctly the first time! Thanks for letting me know. Would it be okay if I paraphrase what you have written above when I go back and edit? Thanks for the comment.

Sure, but my explanation is not perfect - I don't know how much of the negative pressure is due to cooling gasses and how much is water condensing (which you can observe). A great use of the demo is to beware of explanations that do not actually fit the observation - like bad science. If time permits, further investigations might help to complete the explanation.

MrFrancis4 years ago
Great experiment, trying with the kids ASAP!
MicioGatta4 years ago

I did this experiment with a candle and blue ink in the water. My pupils loved it so much that we did it lots of times when talking about air and lots of time at the end of the year with no links to the subjects.

Biodynamic (author)  MicioGatta4 years ago

I probably should have added some dye to the water in the video. Oh well, next time!

A cool bar trick into an awesome teaching lesson, well done sir! Thanks for sharing!

Biodynamic (author)  MsSweetSatisfaction4 years ago

Thanks!

kode13034 years ago
Yes oxygen, a gas, is expended, but the end product of the combution is CO2 and H2O (g), which are gasses too. The main reason for the drop in pressure, I believe, is when the warm (from the flame) air inside the glass cools down and thereby shrinks :-)
Biodynamic (author)  kode13034 years ago

Thanks for the correction! I'm going to go back and edit ASAP.

oldmicah4 years ago

great experiment! I've got a kids activity for tomorrow. Thank you for sharing.