Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
An example of a material categorization task. Three of these images contain plastic surfaces while the rest contain nonplastic surfaces. The reader is invited to identify the material category of the foreground surfaces in each image. The correct answers are: (left to right) wood, plastic, plastic, leather, plastic, and glass.
