He called on the First Minister to fund a “proper, fair pay rise” for school staff after unions rejected councils’ offer of a rise of up to 3%.
Teaching unions have asked for a 10% wage increase, however local authorities said their offer is “best and final”, adding that they have not received extra money for pay awards from the Scottish Government.
Mr Leonard raised the issue at First Minister’s Questions at Holyrood.
He said: “Under the SNP government teachers have seen the value of their pay fall by 25%.
“Scotland’s teachers have gone from being amongst the best paid teachers in the developed world to being amongst the worst.
“They have seen 3,500 of their colleagues disappear from the classroom. They are now teaching some of the biggest classes in the western world.
“We cannot close the attainment gap between the richest and poorest children in our schools with underpaid and overworked teachers.
“The only thing which can stop our schools facing industrial action and our children’s education facing disruption is the Scottish Government finally paying teachers what they are worth.”
Nicola Sturgeon said negotiations over pay were under way, involving unions, councils and the government.
“The government are involved in these negotiations, they will continue I hope constructively, and I hope we get to an end result here that avoids the scenario Richard Leonard has outlined,” she said.
She added: “Local government budgets are being increased in real terms in the coming financial year.
“In terms of teachers pay, I make no apology for the fact that we will take forward discussions in the proper way, through the tripartite negotiation framework that is in place.”