How can an object less than a millimeter wide be measured? Students use a key-chain laser pointer to measure the width of three micrometer-size objects—a fishing line, copper wire, and a strand of human hair. As the laser light bends around each object, students analyze the diffraction patterns produced. Concepts such as wavelength, diffraction, and constructive and destructive interference become clear as students calculate the width of each object. When students compare the experimental values with the accepted values, they will be astonished at the accuracy of this “high-tech” method of measurement! Teacher Notes with sample data, extensive background information and reproducible student worksheet are provided. Includes six laser pointers, fishing line, copper wire, and materials to make frames for the objects being measured. Students supply their own hair. Complete for a class of 24 students working in groups of four.