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I have been learning how to work with Arduino Uno R3, and it seems very intuitive and exciting for me. As many agree, I see lots of benefits of learning to use it at a young age.

I would like to start a volunteer class for the local kids in my neighbourhood to teach them how to start small projects with the Arduino. This also includes learning how to work with a breadboard and other related devices and objects that go along with creating cool projects with Arduino.

What are the safety concerns of teaching 10 to 15 year olds to work with an Arduino (or similar) microcontrollers? Is there an existential risk that is high enough to make it a bad idea, legally or otherwise, to teach such a course to kids that age?

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    \$\begingroup\$ Are there risks? Yes. Are those risks greater than the risks kids take being kids? No. \$\endgroup\$ – whatsisname Nov 21 '14 at 4:08
  • \$\begingroup\$ Existential risks? About the only one I can muster, offhand, is thinking that, somehow, teaching a machine: "Hello World" can confer superhuman powers on the teacher. \$\endgroup\$ – EM Fields Nov 21 '14 at 6:20
  • \$\begingroup\$ yes, indeed. Just as long as angst != risk. \$\endgroup\$ – placeholder Nov 21 '14 at 6:30
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    \$\begingroup\$ If you want to have it safe from capacitors which could bang etc just make a shield with some leds on it + display + switches + capacitors + motor + some jumpers. That way you can let them experiment with programming without the fear they changed the polarity by accident etc. \$\endgroup\$ – Handoko Nov 21 '14 at 7:05
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    \$\begingroup\$ Just a note, an Arduino is not a microcontroller. Its a development platform. Arduino's use Atmel's 8bit AVR microcontrollers. \$\endgroup\$ – efox29 Nov 21 '14 at 8:38
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The biggest risks are that they destroy the equipment, not that they get hurt. At least not until you introduce them to soldering irons!

I would recommend not using lithium ion batteries for power - since they can explode if shorted. Regular AA batteries will get hot if shorted (enough to cause burns/fires after awhile) but arent likely to explode. The best power supply would be one with an adjustable current limit which helps avoid damaging equipment or people.

Some components like capacitors can explode if run over their voltage rating or with polarity reversed - sometimes with a very scary bang. But even that isnt too risky unless it gets in your eyes.

As long as they dont do anything incredibly stupid they will be fine. Electricity at the voltages used in microcontrollers isnt going to hurt anyone.

(As an example of "incredibly stupid" - in our high school electronics lab someone decided to find out what happens if you short out a 120v electrical outlet with a piece of solder. The answer is that it glows for a second, then violently explodes and sprays molten solder a good 10-15 feet. I recommend not repeating that experiment!)

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  • \$\begingroup\$ An alternative to using batteries could be powering the board with an USB charger, if the situation allows for this to be done. \$\endgroup\$ – Giulio Muscarello Nov 21 '14 at 12:48
  • \$\begingroup\$ @GiulioMuscarello As long as they are good USB chargers that will shut down on overcurrent. There are plenty of cheap ones out there where they skipped over every single safety mechanism and a short in those may cause a fire. \$\endgroup\$ – Grant Nov 21 '14 at 13:22
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  1. This probably goes without saying, but avoid using power sources with significant "oomph", or have some mechanism that limit the current/power that is hard to get around. Certainly less than 12V is good, and preferably limit to 1A or less.

  2. Along with 1, batteries are trouble (namely Lithium based batteries). They generally can provide a lot of current when shorted, and in the case of Lithium-based batteries (Li-ion, Li-Po), can catch fire if abused.

  3. Polarized capacitors are trouble (electrolytics/tantalum). When reverse biased, they don't behave like capacitors, but usually like a short. With enough current, the capacitor will heat up. In the case of electrolytics the electrolyte will evaporate, and the cap will burst. I believe tantalum ones will catch fire. Note that there are bipolar (non-polar) electrolytic capacitors. These are perfectly fine to use.

  4. Do encourage good circuit practices from the start. These include (but are not limited to):

    a. Turning off/disconnecting all power sources before modifying a circuit

    b. Keep circuits relatively well organized (you may want to provide layouts for the students to build). This will not only reduce errors, but hopefully will make debugging easier, and decreases the likelihood of anything dangerous happening.

    c. Double checking (or triple checking) never hurts. You'd be surprised (or maybe not so surprised) how often students ask why their circuit isn't working just to find an obvious problem because it was "too simple" for them to check.

That being said, it sounds like a perfectly fine idea to me teaching kids about circuits.

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  • \$\begingroup\$ 3 is certainly good advise. I still have some remains of a tantalum cap stuck to the roof in my office, from when I got the brilliant idea to plug in a new, untested PCB prototype with no current limit on the power supply :) On a more serious note, you probably want to avoid tantalum caps anyhow, because they are one of them "rare earth minerals" where the price might suddenly escalate. \$\endgroup\$ – Lundin Nov 21 '14 at 14:47
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Safety? There is only one thing to be done. Teach them not to stick their faces directly over the circuit. Stand back when you turn on the circuit "just in case". A few "flame ons" here and there will then only hurt your pocket book and make you look sooooo much cooler. Faux danger and learning all in one.

Learning by explosion/smoke/heat is as valid as any other and perhaps more so.

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I was breadboarding with TTL from an early age, back in the days when solder had a lot more lead, a TV chassis was live, and mercury tilt switches were clear glass bulbs freely sold with no awkward questions.

Steel wool and jumper cables were the limit of our destructive nature. Although not many speaker cones survived for long either. Once or twice we did very dangerous things with multi-tapped transformers and CRT yokes from those same TV's.

We did this in sheds where asbestos was routinely cut and nibbled. One of my lay friends went home one day and told his parents I made bombs in the garage. This took a while to die down even in those days.

As for short circuiting, the "crowbar" approach always held an allure. After all it does protect everything downstream and the fuse is serving a purpose.

Nowadays every home should have RCD/earth leakage protection and our work areas a big fat red mushroom switch.

Boards and shields with screw terminals and pins are way safer.

My wife has a Master's and does not what to do with a soldering iron.

Should you get your Raspberry Pi on and teach them to code instead ? If anything this is more dangerous and they probably won't learn any more Python once they realise that C projects run 10 times faster.

It bothers me dreadfully that these processors are often used as sledgehammers to drive in thumbtacks. Many applications could be served by dedicated devices such as 555 timers or counter-scalers. Maybe we just like to dabble.

Anticipate fire, anticipate burns. A bucket of sand for fire. (I still wonder how we could make DC powerpacks for 5V and 12V and use the same connectors) - can't have halon any more either.

Of course, then there is the risk from the project. Let's say a controller for a live steam engine. What are the risks from a sketch gone bad ?

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    \$\begingroup\$ How does any of this answer the question at hand? It's just a long series of random thoughts. \$\endgroup\$ – Dave Tweed Nov 21 '14 at 14:35
  • \$\begingroup\$ I apologise, I did not realise an enumerated list was required. The question is asking for a detailed risk analysis ? What (expletive) risks ? Little Johnny might prick his finger on a piece of wire ? The OP is looking to leverage someone else's policies perhaps, so that he can produce a plan if and when they might be sued..... \$\endgroup\$ – mckenzm Nov 22 '14 at 3:56
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The only risk I can think of is short circuiting. If they are working with batteries make sure to explain this. The danger of short circuiting is for one that it can make the wires really hot. If a battery is short circuited with something of low resistance, like a wire, it could potentially cause the battery to explode.

The Arduino limitations should be taught as well, so they don't damage the controller, for example (by a too high current drawn from and/or too high input voltage on pins).

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  • \$\begingroup\$ Please explain what the dangers associated with short circuiting is? \$\endgroup\$ – Lyndon White Nov 21 '14 at 4:29
  • \$\begingroup\$ added it to my answer \$\endgroup\$ – Harpreet Singh Nov 21 '14 at 4:36
  • \$\begingroup\$ I agree that shorting a battery would be about the worst that could happen. It might be best to avoid using batteries on their own if you can - if you can use a power supply with current limiting (or a way to get battery power through a current limiter), you could make your setup a bit safer. \$\endgroup\$ – Greg d'Eon Nov 21 '14 at 4:46
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    \$\begingroup\$ I'd say "burst" is a better description of what will happen with the batteries if short circuit. They can get crazy hot, possibly start on fire, but it would be rare for them to actually explode. \$\endgroup\$ – whatsisname Nov 21 '14 at 4:51
  • \$\begingroup\$ @whatsisname very true - for typical alkaline and nimh batteries. However, shorting some types of Lion batteries can make them "vent with flame" and turn into a little fire spewing rocket. \$\endgroup\$ – Grant Nov 21 '14 at 5:03

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