IsoplotR is a free online tool with a lot of flexibility for creating diagrams from isotope ratios, particularly for use in geochronology. This is an online version of the usual Isoplot add-in for Microsoft Excel.
Jane’s Geological Adventure
This is a great story by Matthew Fox, all about the geological cycle from the perspective of a Zircon Crystal! Another great example of how to engage kids in Geoscience. You can buy your copy here. All proceeds go to The GeoBus