You are currently browsing articles tagged demos.

After using the iPad2 and the Apple TV to mirror iPad content through my LCD projector, I realized that this setup can be used as a wireless document camera by using the built-in camera app on the iPad2.

The Setup:

First of all, I setup a ‘stand’ for the iPad, so that it could project anything underneath it.  Being a science teacher, I have access to plenty of lab stands and clamps (I actually wrapped the two metal rods in electrical tape to protect the iPad2 from scratches).


I gently rested the iPad2 on the stand, being careful to center the camera on the lab table below, and secured it with a large rubber-band.



I found that I needed a wide stand so that students could fit their whiteboards underneath without difficulty.


This system is also flexible, as it is wireless.  I can carry it back to the lab and showcase individual student work to help direct a laboratory investigation.  Taking a picture, I was even able to annotate over a photo by importing it through an app like the Educreactions Interactive Whiteboard app.


Tags: , , , , ,



Tags: ,

For more than a decade, I have made a fire-breathing pumpkin for my chemistry students around Halloween (see footage from 2008).  After seeing recent posts about making a Flamethrowing Jack-O’-Lantern, I have decided to share how it’s done.  It’s really quite simple, once you have all of the equipment.

Watch the Video:

1. Obtain the Equipment:

  • pumpkin
  • candle
  • carving utensils
  • rubber tubing/funnel (or turkey baster*)
  • cork-borer (same size as rubber tubing)
  • lycopodium powder*

The lycopodium powder is the hardest to obtain (unless you are a science teacher).  I ordered mine from Flinn Scientific.


2. Carve the pumpkin and insert the candle

I like carving a large mouth and eyes (remember the flame comes through every hole).  I used a bunsen burner to add a little detailing.

3.  Bore a hole in the back of the pumpkin

Ideally, this should be a few centimeters above the top of the candle.  If it’s too low, then you’ll blow the candle out.  Insert the tubing through the hole, and attach the funnel on the end.


4. Add the Lycopodium powder and BLOW!

(*during trick-or-treating tonight, I substituted the hose/funnel for a turkey baster, which worked quite well)


The demo works because Lycopodium powder has a high surface area.  When aerosolized, it easily ignites with a flame.  This is actually similar to what happens in a grain elevator explosion:

The work there also tends to be dangerous. Farmers take their grain to elevators to be stored, and sometimes processed, before it is marketed or sold. Fine, highly combustible grain particles flow through the buildings as corn and other grain are moved. A spark from equipment or perhaps a cigarette can ignite the dust, sending a pressure wave that detonates the rest of the floating dust in the facility.

Tags: , , , ,

img_1773After being frustrated with my students not being able to see all of my demonstrations, I decided to make a demo cam with some of my electronic junk.

The demo cam is simply an old Sony Handicam Digital 8 camcorder mounted on an inexpensive Videosecu Universal Camera Mounting Bracket.

The camera has an adapter that splits into an RCA video/mono audio cable, which I can easily plug into my classroom television.  Switching the input on the TV is a piece of cake, and using the TV doesn’t interfere with the interactive whiteboard.

Here are some of the benefits:

1.  I can project demos onto the television above, so the entire class can see every bit of the demonstration.

2.  The zoom function is quite impressive; I can easily zoom in on discreet parts of the demonstration not easily seen – even by the person doing the demo.  This is made even easier with the use of the remote control.

img_18133.  Safety.  The demo cam allows me to show demos without the need for the students to come anywhere near it; it also is far enough away from the demo so the camera is not damaged as well.

4.  Because I have to use the record function to keep the image on screen, I can easily capture video of the demonstration.  As there is a firewire output, I can easily capture the video with a connected laptop, and share it online (below see video demonstration of adding sodium to water).

Sodium in Water from Brian Bartel on Vimeo.

5.  I can also capture slow reactions over a long period of time, import them to a computer and speed up the video to a shorter time (see video of copper in silver nitrate solution).

Some of the Drawbacks:

1.  The angle is a little ackward because of the mounting limitations.  It takes a little practice not to walk in front of it, and to make sure that the demo is in the viewing area while zooming.

2.  In order to use the TV as a monitor, I have to use the record function.  This requires me to stand on a stool, and manually rewind the tape every hour (it cannot be done with my remote).

Tags: , , , ,

Usually the during the week of homecoming, my Biophysical Science class is just finishing up a basic chemistry unit on the properties of matter.  To keep the kids focused on science, I make sure to obtain a little dry ice to have my students observe a unique phase change known as sublimation.

We observe:

  1. Sublimation of dry ice
  2. Density of carbon dioxide (bubbles with hover over more dense carbon dioxide – see video)
  3. Carbon Dioxide as a liquid (under pressure) as it exists in a gas cylinder
  4. Carbon Dioxide as a liquid (by sealing off a pipette with pliers, students can safely observe carbon dioxide liquefy as the pressure increases – see phase change diagram of carbon dioxide)
  5. Rapid sublimation of carbon dioxide in water in a sealed Nalgene bottle (see videos below)

CO2 Expansion 2007 from Brian Bartel on Vimeo.

Note the rapid condensation that appears on the lab table once the pressure is equalized.

CO2 Expansion 2008 from Brian Bartel on Vimeo.

NOTE: this demonstration was done behind a Plexiglas screen when there were no kids in the room.  Below is a picture of the bottle before, after, and a piece that was lodged in the ceiling (of which I am quite proud).

Nalgene Bottle Before

Nalgene Bottle Before

Nalgene Bottle After

Nalgene Bottle After

Piece Lodged in Ceiling Tile

Piece Lodged in Ceiling Tile

I should emphasize that this rapid buildup of gas pressure can be very dangerous.  In fact, the rapid vaporization of liquid nitrogen in a sealed plastic container is exactly how I once blew up a sink (see About page).  This is why a safe alternative to a live demo is to take an extreme video for future use.

Tags: , , ,