Jamieson, Fausset and Brown on 2 Chronicles 17:7-11

7-11. Also in the third year of his reign he sent to his princes, ... to teach in the cities of Judah--The ordinary work of teaching devolved on the priests. But extraordinary commissioners were appointed, probably to ascertain whether the work had been done or neglected. This deputation of five princes, assisted by two priests and nine Levites, was to make a circuit of the towns in Judah. It is the first practical measure we read of as being adopted by any of the kings for the religious instruction of the people. Time and unbroken opportunities were afforded for carrying out fully this excellent plan of home education, for the kingdom enjoyed internal tranquillity as well as freedom for foreign wars. It is conformable to the pious style of the sacred historian to trace this profound peace to the "fear of the Lord having fallen on all kingdoms of the lands that were round about Judah."