Reinventing Morse: Build your own Telegraph


Bennett Harrisby:Bennett Harris

If you are a science teacher who has ever taught a physical science class or attended a physical science workshop then you’ve probably done the activity where you wrap a piece of magnet wire around a nail and use it to make a paper clip or another flap of metal move in response to an electrical current flowing in the wire.  This experiment is often called “building a telegraph” and its a good way to illustrate electromagnetism.  The experiment usually goes over well with students, but from experience I’ve found that this simple activity has a lot of stumbling blocks for younger kids and have always thought that it should be possible to teach MORE with your half hour or less activity time.  To that end I’ve created the Reinventing Morse: Build your own Telegraph science kit.  This article will explain some of my educational design choices for the kit and give teachers or anyone using the kit for educational purposes a few tips to help them in the classroom.Build your own Telegraph

Fun Fact: Even though making a piece of metal slap into another piece of metal using an electromagnetic field makes a click, this kind of simple apparatus is not actually a telegraph sounder.  To be a true telegraph sounder the device must be capable of making a click on both ends of its travel.  This is how a telegraph operator can distinguish dots from dashes, by noting the time difference between the up and down click’s for each “bit” of code that comes through.  Reinventing Morse is designed to operate as a real sounder because the arm makes a click on both ends of travel. Read the rest of this entry »


Silicon from Sand


Carl Ahlersby: Carl Ahlers

SiliconNext time you step onto the beach, bend down, grab a handful of sand and admire the fact:   By mass 47% of what you hold in your hand is the element silicon. The rest is simply oxygen.  Remarkable!

Silicon is the second most abundant element in the earth’s crust (27.7%) – only oxygen beats it – and can easily be extracted from white sand (SiO2) in a spectacular reaction in the school science laboratory.

Thermite Reactions

In Thermite reactions metal oxides react with aluminum to produce the molten metal.  These redox reactions require substantial activation energy to get going and are highly exothermic.

They have been used industrially for welding (even under water), the preparation of metals from their oxides (reduction) and the production of incendiary devices.  The process is initiated by heat but then becomes self-sustaining. Read the rest of this entry »