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Crop circles first appeared in the 1980s in farmers' fields in the UK and reports of them spread over the following decade across the world. The patterns were often geometric and complex, leading to theories that they were created by aliens, though they were likely human-made. Students used GeoGebra to model dynamic crop circles, though some geometries were too complex to create dynamically. Their files were uploaded to a GeoGebra project page on crop circles.