Wednesday, February 4, 2015

Prelude to the Winds: Experiment 2, Warm Air Rises

I promise I practiced my presentation several times before giving it to the kids this time.  I could NOT get this to work until I changed the procedure significantly.  The photo above shows my interpretation of the instructions.  I have a knitting needle affixed to the tray with poster putty.  I cut a spiral from paper and balanced it with a pinhole on the tip of the knitting needle.  I put one tealight candle beneath.  NOTHING HAPPENED.  So, next I tried adding more candles.  Below is the video I took with four candles.

PRACTICALLY NOTHING happened.  The spiral wiggled a bit.  It is supposed to spin.

On the internet I found some science teachers doing this with a burner instead.   So then I amped things up A LOT and held it over our turbo gas burner.  The first time we did it, it not only spun but inverted itself and spun so we had a tornado.  Every time I tried to video this it wouldn't spin but did invert itself as you can see below.


Oh dear.  I had a lot of fun and the boys thought it was hilarious that I started things on fire multiple times while practicing.

What is beautiful about this presentation as it is in the albums is that the child can do it himself on a tray in the classroom.  Also, the child can really understand that it is the hot air causing the movement rather than something magical about the materials because they make their own spiral and assemble this themselves.  Once they understood the concept, I thought it might be neat to bring out something special like  the German candle pyramid I saw at Our Happy Homeschool or these Scandinavian Christmas Angel Chimes I bought.

I took a video so you could hear the gentle tinkling of the bells.


If you would like to see a neat series of YouTube videos showing different experiments that demonstrate that hot air rises, check out Jared Hottenstein's series.  He has several.

The spiral.

Tea Bag Take Off

 I LOVED watching the birthday candle hot air balloon.

He has several more experiments on his YouTube channel.


  1. Very cool. I am going to have to try that bag birthday candle thing. With a fire extinguisher. Your videos are great too! Love the one of Me Too lighting it up!

  2. Ours worked when I got a cheap store-bought candle that burned at a high temp BUT I think our spiral was longer...

    Our awesome-smelling Partylite candles (and any of the "good" ones - and some of the cheap ones) didn't work because of the low temp they burn at.

    I WANT one of those Christmas things! I have seen them in a couple places now!

  3. I should add too - EVERY time I have done this demo, it has had different "needs". I wonder how much has to do with the temperature of the air, any other drafts, phase of the moon, height of the tide, etc. ;)

  4. The presentation I was shown looks exactly like the pic you have of the angels. It was so pretty. Except the candles were taller. I never thought it might not work depending on the actual candles you use and what not. thanks for the tip!