I don't ever plan on teaching high school math, but you never know. This looks helpful.. maybe for friends still in college.
An Alternative Africa - where the Black Plague had almost completely wiped out Europe's population.
Metal Detector Circuit
The Lost History of Man
PVC pipe dimensions
Figure 5. Melting points of metals and alloys.
Deep Soil Metal Detector Circuit - Ground Scanner
Beat Balance Metal Detector
The credit card code…