I have been busy putting together many of the very useful calculators and tools for checking work. These have previously been on a site of their own but I have now decided they are more appropriately placed on Mathematics for Students. I have also added a link (Calculators & Tools) on the right hand side here in the Links section. I have taken the opportunity to do some major updating and I will develop this further in the coming months.
I like to use tools like this in class to encourage students to use them independently for checking their work. I know this strategy works – one of my Year 13 students announced during a homework discussion earlier this year that she knew the answer in the text was wrong (it was) because she checked it on WolframAlpha! Happily I have had many similar comments.