What Valley Vista has a Dysart of 1668?
CREATE TABLE "high_schools_in_dysart_usd" (
  "information" text,
  "dysart" text,
  "shadow_ridge" text,
  "valley_vista" text,
  "willow_canyon" text
);
SELECT "valley_vista" FROM "high_schools_in_dysart_usd" WHERE "dysart"='1668';