One of the most promising developments in the use of computers in the science classroom has been the arrival of microcomputer-based labs (MBL) (Tinker 1987; Collette & Chiapetta 1989; Carin & Sund 1989). Microcomputer-based labs use microcomputers to collect and analyze data during real experiments; probes and software are used to measure physical quantities such as temperature, light, sound, pressure and motion (Bross 1986; McMillen & Esch 1984; Marks 1983). In working with high school students and with student teachers, I have found MBLs effective in teaching students science concepts and in motivating students. Microcomputer-based labs offer several advantages over other forms of computer-assisted instruction. Although simulations can be an excellent means of performing activities that would otherwise be too time consuming, dangerous, expensive or otherwise impractical, MBLs allow students to develop hands-on experience with actual experiments; the computer collects and analyzes real (not modeled) data. My high school students found drill and practice programs effective in learning sophomore biology terminology. Drill and practice, however, focus on material with specific right or wrong answers, and my students seemed to simply memorize terms. I discovered that microcomputer-based labs, like simulations, were ideally suited for inquiry and for the development of higher-order thinking skills. MBL experiences provide several advantages over traditional approaches to laboratory work. Often, data may be graphed in real time; students can see the data graphed as it is being collected. The time saved by not having to construct graphs is remarkable, leaving time for collecting more data, conducting additional experiments, or working on other assignments. In some cases, the computer can collect data when students are not available, such as overnight or during weekends. The computer may also create graphs that students cannot create; this is often true when I work with younger students, remedial students or special education students. There may be an additional benefit in using computers to construct graphs. Mokros (1987) found that middle school students who used microcomputer-based labs improved their ability to interpret and use graphs. At some point I want my students to create their own graphs, but they do this when MBLs are not available. The ability of the computer to construct graphs is especially helpful during demonstrations. By attaching the computer to a large screen TV monitor (or by using an LCD projection pad), I have graphs that are immediately created, easily visible and often easily printed. Igelsrud and Leonard (1988) have done an exemplary job of discussing interfacing in the biology classroom, as have Westline and Bahe (1986). However, their work focuses on homemade or do-it-yourself devices, and does not mention commercially available MBL packages. Homemade interfaces are certainly much less expensive than commercial programs and have the advantage of being tailored to an individual's needs. However, most biology teachers do not have the the expertise or the equipment to construct these devices. I certainly did not have the patience to construct them; despite money saved, I found assembling homemade interfaces frustrating. Commercial labs have the advantage of being preassembled, pretested and covered by warranty. Most are simple to work and are well-designed. Many labs offer sophisticated graphics capabilities and have a professional look to them that is attractive to students. The chief drawback to many commercial labs is cost. Ideally, a teacher purchases multiple copies of programs so that students work in pairs at separate computer stations. Unfortunately, many teachers have only one microcomputer in the classroom; those with more computers can usually not afford to buy multiple copies. At Hamett Central High, I was fortunate enough to work for a school system committed to computers in the classroom. My computer lab had 25 Apple IIe computers. I also received a GIFT grant from the GTE corporation that allowed me to purchase a significant amount of software. At the University of Pittsburgh at Johnstown, I work in a lab with 28 Apple Ilgs computers. Despite these resources, I usually purchase single copies of MBL programs. Even though all students are not doing the same thing at the same time, I do provide my students with a larger variety of experiences. Several strategies exist for using only one microcomputer with a class (Wainwright & Gennaro 1984). Often, I allow one group to work with a microcomputer while others complete another activity. With this rotation James K Stringfield, Ph.D., teaches at the University of Pittsburgh at Johnstown, Johnstown, PA 15904.