Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_13525 ( "School" text, "Location" text, "Mascot" text, "Enrollment" real, "IHSAA Class" text, "# / County" text, "Year Joined" real, "Previous Conference" text )

### Question ###
What year joined had an enrollment less than 438 and an AA as the IHSAA Class?

### Accurate SQL ###

SELECT "Year Joined" FROM table_13525 WHERE "Enrollment" < '438' AND "IHSAA Class" = 'aa'