If you read blogs to keep up with new websites and resources then you have probably heard of Wolfram|Alpha. This Web resource is brought to you by the folks who created Mathematica.
Wolfram|Alpha is a computational knowledge engine designed to make “all systematic knowledge computable and accessible.” Try it out. I entered my birthday and saw not only my age in years but with the added attraction of months, days and weeks. Click on “More Formats/Calendars” for additional information.
Enter a city and state and Wolfram|Alpha offers the population size, time, weather, etc. This computational knowledge engine is suitable for K-adult. In the FAQ it is indicated that “On the elementary end, Wolfram|Alpha can do arithmetic showing steps, make clocks, work with colors, and so on.”
Try this site out if you are datavore. Excellent site for student use too. Check it out and see how it can be used with your students. Wolfram|Alpha includes a FAQ, blog and downloads if you would like to add it to your website.