The https://prooftoys.org/ website presents logic and basic mathematics
of the real numbers. It includes a practical embedded deductive system
for learners whose background may be just ordinary high school mathematics.
The site includes:<p>1. An introduction to logic through pictures, basically interactive Venn
diagrams with explanation. This is a point of view on propositional calculus.<p>2. A brief presentation of the rules of the logic of "simple type theory" at a
raw beginner's level.<p>3. A number of completely rigorous simple proofs, some in pure logic,
and some about real numbers, starting from the classic "complete ordered
field" axioms that define the behavior of real numbers. The proofs are all
done by computer from the ground up using the logic and axioms
(with a handful of gaps). The proofs are all available for reading
online, down to any level of detail, interactively, and at the reader's discretion.<p>4. A web-based tool that lets you build and edit your own proofs.<p>I am seeking user input on the site, and will gladly answer all kinds of
questions as far as I am able.