Kim Thompson was a teacher looking for a way to get kids interested in multiplication; her twin sister, Karen Hilderbrand, was an engineer looking for a way to help her sister. Together, the two wrote a rap song about multiplication. You know how these things go: the song led to an album, and the album eventually led to a company, Twin Sisters Productions, which saw the sisters quitting their jobs and devoting themselves to creating educational aids full time. The sisters' company now offers materials that help with foreign-language acquisition, infant development, homeschooling, Christian music and a lot more. In 2000, the sisters sold their company to a Canadian company called Cinar, but Cinar struggled so they bought it back and have retained control ever since.