A real world example for the divide and conquer method
Back around 1985, Susan Merritt created an Inverted Taxonomy of Sorting Algorithms. The idea is that to sort an array you have two phases, the split phase and the join phase. She divided the various algorithms into two types easy split/hard join and hard split/easy join varieties. Merge sort is of the former type. Quick sort is the latter. 

But all sorts, envisioned in this way are divide and conquer. Her original paper (part of her doctoral work) is a wonder and worth exploring by any CS teacher.