Kit Fine asked me for suggestions of online logic materials that have some interactive component, i.e., ways for students to build truth-tables, evaluate arguments, translate sentences, build models, and do derivations; ideally it would not just provide feedback to the student but also grade problems and tests. There is of course Barwise & Etchemendy’s *Language, Proof, and Logic*, which comes with software to do these things very well and also has a grading service. But are there things that are free, preferably online, preferably open source?

- First we have David Kaplan’s Logic 2010. It’s written in Java, runs on Windows and Mac, is free but not open source, and has a free online grading component. It goes with Terry Parson’s
*An Exposition of Symbolic Logic*, which is also free. To use the software and grading service, you’d have to make arrangements with David. The text does propositional and first-order logic including models and Kalish-Montague derivations. I haven’t tried the software, but it’s used in a number of places.

[Free software ✓ Free book ✓ Online ✗ Open source ✗] - UPDATE: Carnap is an open source framework for writing webapps for teaching logic written by Graham Leach-Krouse and Jake Ehrlich. It comes with a (free, but not openly licensed) online book, and currently can check truth tables, translations, and Kalish-Montague derivations (and they are working on first-order models). Students can have accounts and submit exercises. The software is written in Haskell and is open-source (see Github). It’s used at Kansas Sate and the University of Birmingham.

[Free software ✓ Free book ✓ Online ✓ Open source ✓] - Kevin Klement is teaching logic from the (free) book by Hardegree,
*Symbolic Logic: A First Course*. (There’s a newer version that doesn’t seem to be freely available.) He has an online component (exercises and practice exams) with multiple-choice questions, truth tables, translations, and Fitch-style derivations. I’m not sure if the backend code for all of this is available and could be adapted to your own needs. He has provided a version of the proof checker that works with the Cambridge and Calgary versions of*forall x*, and that code is open source, however. I’m not sure if it’s possible to add the functionality he has on the UMass site for saving student work. Neither the book nor the online exercises cover models for first-order logic.

[Free software ✓ Free book ✓ Online ✓ Open source ?] - The Logic Daemon by Colin Allen and Chris Menzel accompanies Allen and Michael Hand’s
*Logic Primer*. It can check truth-tables, models, and Suppes-Lemmon derivations, and generate quizzes. The interface is basic but the functionality is extensive. There doesn’t seem to be a grading option, however. Software seems to be written in Perl, I didn’t see the source code available.

[Free software ✓ Free book ✗ Online ✓ Open source ✗] - Then there is Ray Jennings and Nicole Friedrich’s Project Ara, which includes Simon, a logic tutor, and Simon Says, a grading program. The textbook is
*Proof and Consequence*, published by Broadview (ie, not free). It does truth-tables, translations, and Suppes-style derivations, and also no models. It requires installing software on your own computer, but it’s free and runs on Windows, Mac, and Linux. The software is free but not open source. I haven’t tried it out. (That website though!)

[Free software ✓ Free book ✗ Online ✗ Open source ✗] - Wilfried Sieg’s group has developed AProS, which includes proof and counterexample construction tools. I don’t think these are openly available, however. It’s used in Logic & Proofs, offered through CMU’s Open Learning Initiative. According to the description, it’s available both as a self-paced course and for other academic institutions to use for a self-paced format or for a traditional course with computer support. Not sure what the conditions are, whether it’s free or not, and have inspected neither the texts nor tried out the software.

[Free software ? Free book ? Online ✗ Open source ✗]

Do you know of anything else that could be used to teach a course with an online or electronic component? Any experience with the options above?