Peter works for Education Development Center (EDC) in Gardiner, ME. He works with educators to improve mathematics instruction K-12, including using technology to improve student outcomes. Many of his work with GeoGebra is either helping teachers learn to use GeoGebra with students or creating tools that incorporate mathematical visual representations. Most of his work is published under the GeoGebra user "EDC in Maine" at [url]http://www.geogebra.org/edc+in+maine[/url], not under this user. Please contact Peter at ptierney-fife@edc.org with any questions or to let him know about problems or errors with any GeoGebra worksheets either here or listed under the user "EDC in Maine". Thank you!