This animated YouTube video, created by Southwest Center for Microsystems Education (SCME), illustrates how DNA microarrays work in the context of nanofabrication. The animation and associated narration describe "how a DNA microarray identifies complementary DNA (cDNA) strands from a sample. On the substrate of the array are synthetic ssDNA stands or oligonucleotides (oligos). Each grid in the microarray contains hundreds to thousands of oligos with a unique DNA sequence. These oligos hybridize with cDNA from one of two samples. There are thousands of grids on the array allowing for the simultaneous identification of thousands of different DNA sequences. Each sample cDNA is "tagged" with the red or green tag as shown in the animation. The "tags" enable an interpretation of the DNA hybridizations." A supporting learning module and activities can be downloaded from the SCME website.