Who were the champions in years where michigan technological university was in third place?
CREATE TABLE "table1_2331549_1" (
  "year" real,
  "host_city" text,
  "host_school" text,
  "champion" text,
  "second_place" text,
  "third_place" text
);
SELECT "champion" FROM "table1_2331549_1" WHERE "third_place"='Michigan Technological University';