From vocabulary study and glossary making I’m going to sentence building. As a starting point, I’m taking the sentence blocks Haugen uses in his Norwegian grammar as exercises (one from column A, one from column B, etc.) and translating them into several languages. It reveals all kinds of things. Haugen also has translation exercises I’ve used and will continue to use, but the sentence building is neat because it highlights not only the grammatical differences among the languages (SOV vs SVO types, ergative subjects, etc.) but also the idiomatic differences, like how you ask politely for something, e.g. Spanish does have “I would like…” but commonly one says “You give me…..” (quisiera una tasa de café vs me da una tasa, and even un cafecito instead of una tasa de). It is daunting. I thought I’d just buzz right through, but the very first one, “The hotel is over there” (Hotellet er der borte) revealed puzzles like articles (Russian and Urdu don’t have them [I haven’t included Latin] which are preposed (Eng, Sp, Fr, Gk) or postposed (Norw, Kweyol). And so on. But it’s like mining the various languages, forcing you to go deep, uncovering gaps in your knowledge, mistakes (Urdu veqa for vaqe = located), things you have forgotten (Sp queda instead of simple esta for located, not to mention esta ubicada or se ubica, etc.)
Fun stuff.