NEWTON Ask A Scientist
Click here to visit NEWTON Ask A Scientist at Argonne National Laboratories, a resource for K-12 students and teachers where working scientists, engineers and mathematicians answered questions in their fields from folks worldwide. The site was organized and run by Steve Sample and Nate Unterman and launched in 1992; unfortunately ANL decided to shut it down in 2015.Over 20,000 questions were answered during its operation.
As a volunteer scientist, I answered questions on this site from 1993 to 2015 and was their longest-serving volunteer (other than Steve and Nate, of course).