Wolfram Research
Wolfram Math World: Triangle Centroid
This site from MathWorld gives a diagram of a triangle with its centroid labeled. The site details how to find the centroid with links to the key terms. The site details many other interesting properties of the triangle centroid.
Texas Instruments
Texas Instruments: Numb3 Rs: Irregular Polygon Centroids
Based off of the hit television show NUMB3RS, this lesson has students explore finding the centroid of an irregular polygon by finding the mean of the coordinates of the polygon's vertices. Further, students find the centroid given that...
Texas Instruments
Texas Instruments: Centroid and Orthocenter
In this activity, students analyze the location of the centroid and orthocenter for different triangles.
CK-12 Foundation
Ck 12: Geometry: Medians
[Free Registration/Login may be required to access all resource tools.] Apply the Median Theorem.
Other
University of Evansville: Centroid
This site from the University of Evansville contains information on the centroid. The information is brief and two picture images are given as well.
Interactive Mathematics
Interactive Mathematics: Centroids
These examples demonstrate how to use integration to find the centroid (center of mass) of an object.