Math word problems

The age old question of "If Jim can mow his grass in 3 hours and .... how long does it take to mow together?"

Watch this.

As a math teacher, I am trying to find ways in which students can solve these problems, without being told how to do it.  I am true believer in discovery method, and I feel as if students discover the solution, then they will truly understand the concept.

I fear, before I started my own transformation, my students were very similar to the one depicted in the video.