My colleague Matt also did science demos for a while, and one day we built a Ruben's tube.

Matt made the tube and the propane supply, and I contributed the sound part - the laptop, amplifier and speaker.

Because of the flames, we did this outside. One thing to note is my CO2 bottle below the laptop and the amplifier. We used this to flush the tube with CO2 so there is no oxygen in the tube when you start flowing the propane [we found out the hard way that this is a useful trick].

• Heinrich Rubens
• A bit of history at Wiki
• With a PVC tube
• How to video
• another detailed build
• Online tone generator
• Make SF Ruben's Tube

In 2018, a bunch of us at Make Santa Fe built an orrery, our contribution to the Interplanetary Festival, which was organized by the Santa Fe Institute.

Not exactly a project that I do in class, but we set up for a few days in the railyard in 2018, and likely again each year for the festival. The orrery now is stored at the Children's Museum, where I set it up a few times per year.

The orrery is hand-cranked, and the (fantasy-) planets have led's in them

• The Orrery project
• What exactly is an orrery?

The Human Body One question that had been sitting on the 'unanswered questions' list for a while was 'Tell us more about the human body'. I decided to do this as a set of distinct systems. This took up 2 sessions.

(1) First, the skeleton. When you are born, you start out with about 270 bones, but by the time you are an adult, the count is 206. The biggest bone is the femur (thighbone), and the smallest bones are found in the middle ear, with the stapes being the smallest. Bones are held together with ligaments, and in between bones is cartilage.
(2) Muscles and tendons: The body has about 650 muscles. The biggest is the gluteus maximus (the buttocks). The smallest is the stapedius, which stabilizes the stapes bone. Sometimes the muscles are located far from where they need to move bones. The muscles that move your fingers are not in your hand, but in your forearm. Tendons conect the muscles to the bones they need to move.
(3) The circulatory system: It can be imaged as a figure-8 circuit: from the heart the blood is pumped to the lungs, where oxygen is taken up, and CO2. (...) heart → body → heart
nervous system: brain - spinal cord - etc Fast signal system Sensory signalt to the brain Muscle commands from the brain
digestive system
cleanup: liver and kidneys
endocrine system Sends chemical sisgnals via the blood slow signal
immune system
Microbiome: bacteria, viruses, fungi, parasites

• The Orrery project
• What exactly is an orrery?

Fossils I brought a book I had 'How to Fossilize your Hamster". Very useful. Terri had a pretty good collection of fossils to show. I went over the basics. you need: rapid burial low oxygen more sediments on top no heat lots of time body fossils trace fossils bones footprints teeth tracks feathers coprolites eggs   permineralization petrified wood mold or cast leaves, shells carbonization leaf films unaltered amber dating fossils

• fosillaria
• NM state fossil: Coelophysis bauri, which weighs about 50 lbs and measures about 6'. Lots of themwere found at Ghost Ranch, not far from here.
• cat scans allow you now to look inside rocks to see the bones inside, without having to cut them open.