A police investigation is underway after £18,000 worth of damage was caused to Hawthornden and St Mary’s Primary Schools in Bonnyrigg.
At Hawthornden alone, 80 skylights and 42 double-glazed windows were shattered on April 7.
Police Scotland and officials at Midlothian Council have assessed the total repair bill for all the damage as being £18,000.
Inspector John Dryden said: “This is an appalling attack on the primary school and the cost of the repair will ultimately come from Midlothian Council’s budget – money that would be better used for vital services to the community.
“It would have taken a significant period of time for the vandals to smash 122 windows and the noise alone must have attracted attention.
“I would also ask parents and guardians to assist in preventing further incidents by ensuring they know where their children are and what they are doing when out and about.”
A spokesman for Midlothian Council said: “It is not just the financial cost to the council, but the emotional cost to our school community.”
Anyone with information is asked to contact police on 101.