Let's up the ante. To challenge the understanding of game situations further, ask the same question but change the score. At 8-6, in my opinion, the answer is the same (as long as there are no outs which is the scenario Joe stated). It might of course change if it's 8-7 and that runner is the tying run. Even then, it's all about calculated risks because there is still a 90% or so chance that the runner at 3B is going to score. On my DD's summer team, I'd want the catcher throwing it b/c if she does overthrow, there is a good chance the LF will nail the runner at home (the 3B coach would be sending her given the penchant for illogical risks shown already).
riots: At 8-6, the answer is absolutely the same. If we overthrow and the runner scores, the tying run will still be coming up to the plate, just as she would if we don't throw and give the runner third. At 8-7, of course everything changes.
You are correct that the decision in my scenario is easy. The much tougher decisions and thinking come in the early and middle innings when things aren't so black and white.
At practice today, we had several players ask for more game situations! We had about a 30-minute discussion last night on the situation I laid out at the start of this thread and they really got into it. When we have those discussions I lay it out and then let them give their thoughts. No matter what they say, I challenge them. I eventually come around to giving my answer, but I try to do it by asking them questions to make them think about every aspect of the situation.
Instead of giving them more situations today, we had them come up with a couple to quiz the coaches about. They enjoyed that. I told them they can grill me about game situations 24 hours a day, 7 days a week, I love it.
The one area in which most girls and coaches and I end up disagreeing about is the value of momentum. That is a topic for an entirely different thread, but needless to say I think it's drastically overrated and should never be used as a reason to chuck overwhelming percentages out the window.