Example Puzzles from Mathe im Advent
Here you can find a small selection of 400+ "Mathe im Advent" exercises, that have been published. They cover different mathematical topics and teach useful applications of mathematics, the value of mathematical thought experiments, as well as the limits of routine calculations and the importance of constraints and prioritization in mathematical modeling.
The exercises are accompanied by a detailed solution and often by sections "The bigger picture" (explaining applications or cultural backgrounds), "Looking beyond the box" or "Mathematical Excursion" (explicating the introduced mathematical concept) or additional open questions "For further thought".
1) Invite All Your Friends! (grades 7-9)
2) Profit Cuts (grades 4-6)
3) Ebb and Flow (grades 7-9)
4) Signing A Big Contract (grades 4-6)
5) Quick Sand Companions (grades 7-9)