All teachers do assessment. Biology teachers, by grading exams, quizzes, papers, and lab reports, assess mostly knowledge. An important part of being a modern biologist, however, is ability to perform certain technical or manual skills (known in trade as techniques) such as running gels, pipetting, recording from excitable cells with microelectrodes, performing tissue culture, and like. Only rarely do we hear that classroom assessment should measure performance in laboratory as well as in general classroom (Heady, 2000). Assessment tools geared toward laboratory usually involve self-confidence surveys, self-reported skills checklists, videotaping of student performances, portfolios, concept maps, and so on (Angelo & Cross, 1993; Lunsford & Melear, 2004). Except for time-consuming videotape evaluations, none of these tools can be expected to measure reliably performance of a technical skill. Instead, these tools typically measure student satisfaction (for example, see Ghedotti, et al., 2004) or student thinking skills such as ability to design an experiment or interpret literature (for examples, see Elwess & Latourelle, 2004; Gilbert & Mason, 2004). To begin to address this dearth of assessment tools for technical skills in biology, I describe in this article a rubric intended to help measure a student's ability to use compound light microscope. This instrument is still mainstay of biologist, and every student would be well-served to master its use. During years of watching beginning students use microscope, I had been unwittingly gathering data regarding mistakes they made. Based on these data, I have developed rubric shown in Figures 1 and 2. I have recently begun to pilot rubric, which is a work in progress, and any instructor wishing to use it will probably want to fine-tune it to fit his or her preferences and needs. For example, shorter forms of rubric can be produced by deleting some combination of Items 1, 2, 5, 6, 9, 12, 15, and 16. The rubric described here does not assess ability to use a dissecting, electron, dark field, phase contrast, confocal, or fluorescent microscope. It does not assess student's ability to make a wet mount. The rubric is designed simply to assess ability to use a compound, binocular, light microscope. I am currently using rubric to obtain a pre-introductory biology and post-introductory biology measure of a student's skill in usage. By doing so, I hope to quantify amount of progress a student makes in developing this skill during our one-semester introductory course (a four-credit-hour course that meets for three clock hours per week in lecture and three clock hours per week in lab). I administer assessment to each student during first meeting of laboratory, and again four months later during final meeting of laboratory. Between taking of these two measures, student spends one entire laboratory period performing a how to use microscope exercise; such an exercise is standard in virtually every commercial laboratory manual for this type of course. The student also spends four laboratory periods performing, as part of a group of four students, a miniature research project involving a protist such as Tetrahymena or Chlamydomonas. This project involves considerable use and thereby provides opportunity to practice skills gained in earlier laboratory period. The rubric described here need not be used in exactly this fashion, however. It could be used to provide a pre-lesson and post-lesson measure of skill attained during a single laboratory period. It could alternatively be used to measure fraction of a group of students meeting an intended learning outcome, or competency (such as the student will become proficient in use of microscope), for a course or program of study. …