The "Technology, Education and Copyright Harmonization Act" was signed into law in 2002 as an amendment to the Copyright Act. It was an attempt to incorporate the educational exemptions given to instructors for face-to-face classroom use into online classes.
Section 110(1) of the Copyright Act (often referred to as the Education Exemption) allows educators to perform or display works (e.g. videos or slides) without needing to worry about copyright. However, this is only during face-to-face classes. As online classes became ever more prevalent, the need to extend those rights to the online world grew more crucial. After several years of meetings between copyright owner representatives, educational representatives and library representatives, a number of recommendations were put into a report to Congress from the Copyright Office. These were used as a basis for the TEACH Act.
The TEACH Act is now Section 110(2) of the Copyright Act and some -- but not all -- of the exemptions offered in 110(1). The act deals with "transmission" of works, not specifically online classes.