March 2, 2011
by: Carl Ahlers
Next 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. Read the rest of this entry »
June 13, 2010
by: Tami O’Connor
When two 1-pound, 2-inch diameter, chrome steel spheres are smashed together, enough heat is generated at the point of contact to burn a hole in ordinary paper! This dramatic demonstration has been a favorite of students in every grade for as long as I have been teaching!
There are a few considerations when allowing students (especially younger ones) to conduct this activity on their own… First, the spheres are pretty heavy, so if they were either dropped on a foot or onto a nice tile floor, the result would not be good. Also, be sure that the only thing between the spheres is paper or aluminum foil. Fingers caught between the colliding spheres would not be happy. Finally, all participants should wear safety glasses, as it is not unusual for a small piece of paper to fly off after the spheres collide.
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