A climber felt from her anchor as they begin/wait to climb the second pitch. As it is the case actually, we don't have any information on what happens. it look like a lack of communication between the leader and the second. http://www.radio-canada.ca/regions/quebec/2013/07/08/005-accident-escalade-mortel-portneuf.shtml
Personally, I use the sequence of three question: I take you on belay (leader)...Do you took me on belay(second) O.K. you can climb (leader). Those signal are constrict on three words: on belay (leader), climbing (second), climb (leader).
I also practice on a slab, where I can watch my partner, to be sure that we use the same communication. Many mistake can be done and some times...and for some people... it can be useless to do such a practice as they can climb hard and talk how good they are after.
Climbing trad, or any situation where a climber have to be in control of his security, is like running a computer. If you run five program in a same time, your computer is going to run slower than if you run one program. In trad, you have to train to place pro, train to have a good communication with your partner, train for route finding, train for run out, route finding, falling, ....
I use the term practice more than train because the former is on a regular basis and the later is over a period of time uniquely