Free Membership - Access to more than just media

Families and school personnel (including those in training) who have at least one student with a disability can sign up for free membership.

A video screenshot of men in midevil costumes featuring our containing closed captioning

Accessible Media

Standards-aligned videos with high-quality captions and audio description.

A screenshot of a video in our Learning Center with an arrow pointing to the Create Clip button

Teaching Tools

Create lessons and assign videos to managed Student Accounts.

A video still of someone doing Sign Language with the closed caption reading 'You can practice reading my signs.'

Training Videos

Educator and sign language training videos for school personnel and families.

Measurement & Scale

24 minutes 36 seconds

Apply for Free Membership

Videos are generally available for preview to non-members as short clips. Limited full-length titles are also available. Log In to view the full length title.

Browse Full-length Non-member Titles

Open wooden box with metal instruments to measure length. Caption. But how did we come up with rulers.

Discusses the use of units in measurement and scale. Segment 1, Weight: Describes the history of finding reliable standards of weight measurement, which started with the traders. Discusses the difference between mass and weight and the origin of the kilogram. Segment 2, Length: Looks at how standard units of length measurement were developed, which include hand, foot, inch, yard, and meter. Explains why measuring length is now based on the speed of light. Segment 3, Scale: Profiles an astronomer who uses scale to study our solar system. Sheldon Schafer has converted the city of Peoria into a scale model of the solar system to help understand the vastness of the scale of the universe. Includes suggested classroom activities after each segment.