Do you think very bright children should be actively taught grammar or are they capable of absorbing it by osmosis?

I am debating whether to provide some grammar resources that are semi fun or at least not deadly dull and encourage DS & DD (rising 4th graders) to polish their grammar skills. They are not bad and likely above average but decidedly lagging other abilities. I guess their grammatical errors bother me a bit.

I am of two minds as to the necessity. I missed all the grammar classes in middle school because GT classes replaced the English classes and for whatever reason the school did not think we need to get grammar instructions. As a result, I would not be able to teach gramar without some kind of resource because I actually don't know a lot of the terms. I don't really know the rules but mostly I write by feel/sound.

Any recommended resources, particular for upper elementary kids?