As you can tell if you actually read that box, an evaluation is not a recommendation.
When should you use which?
Even if all your recommenders fit into the traditional category, you should get at least one evaluations; some law schools require them.
How Do You Create an Evaluation?
You begin in the same way that you create a recommendation. In fact, you start on the same page, and can assign a rec, an eval or both:
Instead of printing a bar-coded form, as you do for a rec, your evaluator will receive an email from LSAC informing the person that you've requested an eval. You must
DO NOT give a generic description of yourself like "History 103." How many people in History 103 asked this person to evaluate them? Instead, give a description that will trigger a clear memory. I went to an Egyptian restaurant with this client, so I won't confuse her with any other clients. Had she written "DC Law Forum," I might confuse her with the others I met at that forum — if I even remembered which year!
Since you may not have as memorable an event, think of some good way to describe yourself: "term paper about Sappho;" "arranged field trip to Monticello;" "walked you to bus stop every Friday." Or there may be some fact about yourself: "lady with the walker;" "you always confuse me with Maria;" "always had a skateboard;" "you laughed at my pink hair."
Finally, you must give a description of the recommender to yourself, to jog your memory. The evaluator may see this description, so be diplomatic.
"History 103" will do nicely here, since you only took the class once (we hope). In those rare cases in which you can take a class more than once without having flunked it [usually a course called "Selected Topics in...," which your school allows you to take several times], be more descriptive: "Aristotle's Politics" rather than simply "Aristotle."
How Do You Submit an Evaluation?
You send an Eval to the the Law schools in the same way you do your recommendations. In the "assign letters" page on LSAC, there's now a button for assigning evals, too.
A link below the school's name shows you how many recs and evals a school demands and accepts. The envelope icons mean that those LORs and Evals have already been sent, and you can no longer change your assignment. However, if you can still see the "Assign" button, you haven't sent the maximum the school will take and can assign more if you wish.