Many varieties of data acquisition systems are now available for science classrooms. Most systems consist of a range of sensors--typically called probeware--connected to an interface unit usually described as a datalogger due to its capacity to record data from these sensors. Although some systems operate independently, most units connect to a desktop computer, handheld computer, or calculator for at least some of the time to allow data to be viewed and manipulated in a range of ways. Some manufacturers produce standalone units with their own data output screens, which do not rely on a computer connection. Part I of this two-part article offers a summary of educational research findings showing the advantages of using such sensors.