Thank you JulieS. It does help. One more question please...

Now, say I have 3 types of modules to teach. I don't want to wait for a module to finish before moving on to the next one. So, instead of having Module 1 start on 01/01 till 10/01, then Module 2 on 11/01 till 20/01, and Module 3 on 21/01 till 31/01, I would like to have something like that: all modules start on the same date. I attribute a number of different trainers to each of them. However, some trainers are attributed to more than one module. Can MS Project assess and track the impact of having some trainers teaching more than 1 module at a time (a trainer obviously cannot be in two classrooms simultaneously)?

Thank you so much