My cousin is coming up to Colorado this weekend and wants me to teach him how to kayak. He is staying in Boulder and I'm from the Vail area so I am not familiar with the runs in that area, especially class I-II.
Lagerman is a good one. 63rd north several miles past Boulder Rez to Prospect, turn right to lake. No fees, no permit, few people.Lagerman reservoir east of 63rd a few miles north of boulder. Boulder Res is hassle given need for kayak permits.
If he really is first timer then lake is best bet anyway. Takes a while to learn to paddle in straight line, forward/backward, various strokes. Let alone learning to roll.