Church Bowl Tree is a classic Yosemite rock climb. Though rated 5.10b, the first pitch is only .10a and it is also an ideal first clean aid lead as well. The protection is abundant and it can easily be aided (at C1) and then top-roped if 5.10a is out of your comfort zone as a trad. lead. Because it is a high-quality route, however, be aware of others that may want to climb it as well and please be respectful.
Once in Yosemite Valley, head towards the Ahwanee Hotel towards the Church Bowl area. Before you get to the Ahwanee, there is a parking area on the northern side of the road. Park here. Follow the path towards the porta-potties. Keep going and the path ends at the base of Church Bowl Tree.
The route starts just to the left of "More Balls Than Brains". It follows a medium to thin crack and the first pitch ends at a pair of bolts with a chain. If you like, there is a bolt ladder leading up and then left for a second pitch but most people only do the first pitch. One rope reaches the ground for rappel.
Small to medium gear. Offset nuts and cams are helpful as there are many pin scars on this route. (Purple/red/yellow/green offset nuts (from .4) are very useful, as are blue/green, green/yellow, and red/yellow Aliens.) Regular nuts and TCUs with a few medium/large (to 1.5) cams are helpful as well.
"How do you distinguish between being off-route and putting up a first ascent?"