The development of probeware--electronic sensors connected to a desktop computer, calculator, or handheld computer, together with supporting software--has revolutionized the conduct of science laboratory instruction and permitted students to engage in true inquiry. Part I of this two-part article offers a summary of educational research findings showing the advantages of using such sensors. Part II, by Nusret Hisim, offers a range of practical suggestions for using probes in laboratory teaching across the sciences.