Geological history of our planet, presentation, nice pictures
5. "Why are all the worksheets docx type? Not everybody can open them."
We support docx files because a lot of people use the new MS Word, where this is the default format. If you use an older version, try installing the Microsoft Office Compatibility Pack for Word. You can download it for free here. This will surely solve your problem. Or go to zamzar.com where you can convert the docx file online into doc format.