Wolfram Alpha is a great way to make the internet work for your students. It takes the input and rather than just searching for it like other search engines, it analyses the input and returns interesting information.  Searching for words can give you the frequency that those words turn up in written language, the date that they first appeared, and lots of other information.  Searching for a statistic, such as population density for example, gives you mean and median statistics on population density, maps showing each country’s population density, and even trends in the data for the last few decades.  Entering works of literature gives students publication information, character lists, and other interesting facts.

Website: https://www.wolframalpha.com/
Subject: Any
Grade Level: Any, as long as students have reading and analysis skills
Price: Free