References:

1. "Creating a Marble Sorter." SchoolTube. Web. 19 Apr. 2012. <http://www.schooltube.com/video/111382ba5fd84be68f81/>.

2. "PLTW Marble Sorter Video - PLTWCa - Video Central." Home. Web. 19 Apr. 2012. <http://video.pltwcalifornia.org/videos/14/pltw-marble-sorter.html>.

3. "Prezi." Prezi.com. Web. 19 Apr. 2012. <http://prezi.com/6wia7qi4nfp8/project-lead-the-way-poe-activity-331-marble-sorter/>.

4. "TeacherTube Videos - Marble Sorter." TeacherTube. Web. 19 Apr. 2012. <http://www.teachertube.com/viewVideo.php?video_id=105427>.

5. Wikipedia. Wikimedia Foundation. Web. 19 Apr. 2012. <http://www.wikipedia.org/>.

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