Rock-climbing has changed the face of human history, from the brave adventurers who first scaled Mt. Everest to the rogue Mt. Rushmore revisionists who first added Teddy Roosevelt’s mustache. Leave your mark on the world with today’s Groupon: for $17, you get a two-hour introductory rock-climbing lesson at ROCK’n & JAM’n, with locations in Thornton and Centennial (a $35 value). Class times for each location are as follows:

• Thornton classes are held Mondays at 7 p.m. and Sundays at 10 a.m.
• Centennial classes are held Tuesdays at 7 p.m. and Saturdays at 1 p.m.<p>

Instructors at ROCK’n & JAM’n invert worldviews as they train students to scale stretches of mountain. Attendees balance and belay along the training walls as teachers impart the essentials of safety, rope control, and which Disney songs echo most effectively off of mountainsides. The regularly updated facility features a slew of updated equipment that utilizes both ancient and recently conceived training methods to promote a well-rounded repertoire of climbing skills. The lesson includes all necessary gear and all-day access to the gym’s facilities after the initial two-hour training session, letting neophytes test their new skills on the rocks in a safe, forgiving environment.

Within both ROCK’n & JAM’n facilities, towering artificial edifices loom in crags and slopes, soaring toward the distant ceiling’s bright lights. Thornton’s adjustable system wall and workout area prepare muscles to wrestle with gravity, and Centennial’s training walls feature every kind of hand, foot, and nose hold within easy reach of the ground.