Another article +Isaac Thacker
shared with me. I'm very interested in seeing how this works out. There was actually a discussion of this type of approach on a Computer Science education list. In that case, it was looking at Discrete Math and whether it should be taught as an independent course, or if other courses should present the required material as needed. That discussion pointed in the opposite direction of what Finland is doing. Departments/faculty who had tried it mostly said that they didn't like it. It had two negative effects. It slowed down the presentation of the other material and made things a bit disjoint because you would have to stop covering X to give students background knowledge in Y. It also seemed that it caused students to get less depth in Discrete Math overall as the only topics that were taught were those specifically required for other parts of the curriculum. There was a third problem as well, that won't impact primary and secondary school as much. That was the issue that at the college level a fair number of things are elective. So you have a lot less control over exactly what Discrete Math students wind up seeing if it is spread around.
I think I see this as a conflict between making things relevant to students and "efficiency" of teaching. It is a standard challenge with many types of approaches. Methods that facilitate retention often move through material more slowly. The argument is, "What good is it to teach something if students don't actually learn it?" That is a valid criticism. However, the better students still do retain things, and no one learns the stuff you never get to.
I also find it interesting how the title mentions math and physics instead of history or other humanities. The text makes it clear this is for everything.