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 CLASS ( crs_code VARCHAR )
TABLE: CREATE TABLE department ( school_code VARCHAR, dept_code VARCHAR )
TABLE: CREATE TABLE course ( crs_code VARCHAR, dept_code VARCHAR )

### Question ###
Find the number of classes in each school.

### Accurate SQL ###

SELECT COUNT(*), T3.school_code FROM CLASS AS T1 JOIN course AS T2 ON T1.crs_code = T2.crs_code JOIN department AS T3 ON T2.dept_code = T3.dept_code GROUP BY T3.school_code