"Des enfants nombreux mangent."
I'm confused... I'm pretty sure there was a sentence in a previous lesson where the structure was "De nombreux enfants" (and "beaucoup d'enfants" wasn't even accepted)... I remember from other lessons I used that the teacher suggested the BAGS rule making it easy to remember when the adjective goes before the noun. The BAGS were beauty, age, goodness, and size. I'm not sure if "many" can fall into the "size" rule, but in any event the structure is not used consistently throughout the lessons, so something is not right.