\input zb-basic \input zb-matheduc \iteman{ZMATH 2001c.01913} \itemau{Franci, Raffaella} \itemti{A wolf, a goat and a bunch of cabbages. (Il lupo, la capra e il cavolo.)} \itemso{Archimede 52, No. 2, 67-76 (2000).} \itemab The river-crossing puzzles occur for the first time in a Latin collection of mathematical problems, the "Propositiones ad acuendos juvenes", written at the beginning of the ninth century by Alcuin of York, chief of the Palace school of Charlemagne. Alcuin presents four crossing problems, the most famous of which concerns a wolf, a goat and a bunch of cabbages. Less known, but perhaps more interesting, is the problem of the jealous husbands that involves three couples, which must cross a river using a boat that holds just two people. Because the husbands are so jealous, no wife can be in presence of another man without her husband being present. This problem can be generalized to n couples. The paper analyses both puzzles and suggests a didactical use of them. \itemrv{~} \itemcc{A30} \itemut{alcuin of york; mathematics in the medieval; crossing problems} \itemli{} \end