Guess & Check strategy?

So...Nathan brought home a math paper today for homework. It had several word problems that he was supposed to use the guess and check strategy on. First of all, this is the first time I've ever heard of this. Second, to me it seems like a hard concept for 3rd graders. Even for an adult, it takes a little extra thinking. Here's one of the problems:

A grizzly bear's life span is 7 years more

than a black bear's life span.

The sum of their life spans is 43 years.

What is the life span of the grizzly bear

and the black bear?

See? Even an adult has to really stop and think about it. After about one hour, he finally finished all six problems...yes, I said only six! I wasn't going to just give him the answers, so I made him work through them on his own with my help. Anyway, all this to say that I don't really think this is a necessary concept quite yet. I don't know...sometimes I think California school standards are too high and hard.