I've gotten a couple of requests to referee papers for the European Journal of Physics, https://en.wikipedia.org/wiki/European_Journal_of_Physics , which is a journal that publishes pedagogical papers (not original physics research). Both of these were for pedagogy papers having to do with relativity, which is in principle a topic I'd enjoy being a referee on, and one on which I think I would typically have sufficient expertise (depending on exactly what the paper was). I did a report on the first one, but now the second request is in my in-box, and I'm thinking that this is probably not where I want to direct my energies, since EJP isn't open-access, and I can't even read it myself. (They theoretically do allow authors to make their papers open-access, but they have to pay $2700 to do so, and clicking through a small random sample of EJP papers failed to turn up any that weren't paywalled.) Is there any open-access physics journal of this type, focusing on education rather than research?