Privacy
The short version: you can use every chart on this site without telling us anything about yourself.
What we do not collect
There are no accounts and no sign up forms. We never ask for a name, an email address or a school. Answers typed into the blank chart or the quiz stay in your browser and disappear when you close the page.
Visitor statistics
We use Google Analytics to see how many people visit and which charts they use most. The statistics are anonymous totals. We do not see who you are and we use the numbers only to improve the site.
Printing and PDFs
The PDF charts are plain files. They contain no tracking and you may copy them freely for home and classroom use.
Changes
If anything on this page changes, the new version will be posted here. Last updated September 2026.