List the top five schools, by descending order, from the highest to the lowest, the most number of Enrollment (Ages 5-17). Please give their NCES school identification number.
SELECT T1.NCESSchool FROM schools AS T1 INNER JOIN frpm AS T2 ON T1.CDSCode = T2.CDSCode ORDER BY T2.`Enrollment (Ages 5-17)` DESC LIMIT 5