.NHExperience with Students..PP.ILearn.Rhas been installed onmany different .UXsystems.Most of the usage is on the first two scripts, so theseare more thoroughly debugged and polished.As a (random) sample of user experience,the.I learnprogram has been used at Bell Labs at Indian Hillfor 10,500 lessons in a four month period.About 3600 of these are in the files script,4100 in the editor,and 1400 in advanced files.The passing rate is about 80%,that is, about 4 lessons are passed for every onefailed.There have been 86 distinct users of the files script,and 58 of the editor.On our system at Murray Hill, there have been nearly 2000 lessonsover two weeks that includeChristmas and New Year.Users have ranged in age from six up..PPIt is difficult to characterize typical sessions with thescripts;many instances exist of someone doing one or two lessonsand then logging out, as do instances of someone pausingin a script for twenty minutes or more.In the earlier version of.I learn ,the average session in the files course took 32 minutes and covered23 lessons.The distribution is quitebroad and skewed, however; the longest session was130 minutes and there were five sessions shorter thanfive minutes.The average lesson took about 80 seconds.These numbers are roughly typical for non-programmers;a.UXexpert can do the scripts at approximately 30 secondsper lesson, most of which is the system printing..PPAt present working through a section of the middle of the filesscript took about 1.4 seconds of processor time per lesson,and a system expert typing quickly took 15 seconds of real time per lesson.A novice would probably take at least a minute.Thus a UNIX system could support ten students working simultaneouslywith some spare capacity.