The Thomasites were originally a group of about 500 American teachers sent by the United States government to the Philippines in August 1901 who arrived on the USAT Thomas. The term however has also been expanded to include any teacher who arrived in the first few years of the American colonial period of the Philippines.

The Thomasites 365 males and 165 females left Pier 12 of San Francisco on July 23, 1901, to sail via the Pacific Ocean to South East Asia. The U.S. government spent about $105,000 for the expedition. More American teachers followed the Thomasites in 1902, making a total of about 1,074 stationed in the Philippines.

The Thomasites arrived in the Philippines to establish a new public school system, to teach basic education, and to train Filipino teachers, with English as the medium of instruction. The Philippines had enjoyed a public school system since 1863, when a Spanish decree first introduced public elementary education in the Philippines. The Thomasites, however, expanded and improved the public school system and switched to English as the medium of instruction.

The name Thomasite was derived from the transport vessel USAT Thomas (earlier known as SS Minnewaska in private service), which brought the educators to the shores of Manila Bay.

More Info: en.wikipedia.org