You'll find it all in Section 1 of Article IX, in the preamble to the education portion of the document, not the preamble to the entire constitution). To wit:
It is the paramount duty of the state to make ample provision for the education of all children residing within its borders, without distinction or preference on account of race, color, caste, or sex.Bonus trivia question: How many articles are there in the Washington state constitution?
Bonus extended dance remix question: What is the official state amphibian? (Hint: Ask the students at Boston Harbor Elementary in Olympia. They lobbied the Legislature this past session to make it official!)