When discussing teaching in the teaching paragraph of your letter, one of the temptations is to tell a chronological tale of how you taught as an adjunct here and an adjunct there, and taught this class in Fall 2012 and this other class in Spring 2013, and will soon be teaching this other new class at the U of X in Fall of 2013.
Resist that temptation.
Search committees actually don’t want to read a chronological narrative of when and where you taught.
They want an ahistorical (so to speak) demonstration of what and how you teach.
Teaching paragraphs can be in the present tense (although this is not a hard and fast rule), and will ideally articulate courses you are prepared to teach, specific courses you have taught (without mention of where or when) or can teach, and most importantly HOW you teach them, using distinctive and memorable methods.
By the way, small group discussions and seminar papers are not distinctive and memorable methods.
Search committees need to be easily able to imagine you as a faculty member in their department. Invoking the names of other universities and colleges is an obstacle to that. In addition, if the other colleges and universities are of lesser status, it has the effect of making you look less-than-qualified for the current tenure track position.
Finally, the chronological narrative also diminishes your status as candidate. It is actually one of the more pitiful things to read in a job letter when a candidate inadvertently discloses his or her adjunct saga, in the same way that it is sad when a candidate is overly enmeshed in his or her graduate school past. Remember that letters for tenure track jobs must never depict you as an adjunct (or a graduate student). Yes, you may have gained teaching experience as an adjunct, and the courses you’ve taught and methods you’ve mastered should be described, but the prior identity itself must be rejected in favor of a presentation of the tenure track faculty peer and colleague identity that is the goal of the application.