#1064 - You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '[schedule.`first`, schedule.`second`, schedule.`third`, schedule.`fourth`] ' at line 4
Возможно, я неверно составил...
SELECT
hw_10.hw as hw
FROM schedule
LEFT JOIN hw_10 ON hw_10.subject_id IN [schedule.`first`, schedule.`second`, schedule.`third`, schedule.`fourth`]
WHERE schedule.student_id = '1'
AND schedule.day = 'Monday'
AND hw_10.`date` = '2014-11-24'