TORONTO -- A sharp exchange broke out between Premier Dalton McGuinty and the Elementary Teachers' Federation of Ontario (ETFO) Monday as the province lost its first school day to labour strife since 2003.

"The Elementary Teachers' Federation of Ontario has disrupted nine years of labour peace over a disagreement about pay," McGuinty said in a statement Monday. "It's regrettable that students miss any time learning, and it's unfortunate that families will need to make alternate arrangements.

"While inconvenient, these one-day legal strike actions do not warrant the intervention of the government and are a small price to pay to protect full-day kindergarten, smaller class sizes and 10,000 teaching jobs," the premier said.

ETFO responded later Monday with a rebuke to McGuinty, saying teachers had been "forced" into striking by his government's Bill 115 and that his comments were particularly offside on International Human Rights Day.

"Bill 115 threatens the very democratic values and institutions like public education that have built Ontario," ETFO president Sam Hammond said in a statement. "How unfortunate that the premier of this province has today trivialized this most important fight against Bill 115 as a disagreement over pay."

Hammond said the labour actions are not related to a wage freeze, but are a response to the loss of the constitutional right to collective bargaining.

Public elementary teachers in the North East and Avon Maitland school boards held a one-day strike Monday -- the first time since McGuinty was elected premier that student instructional time has been lost to job action.

Teacher strikes are planned for the Niagara and Keewatin-Patricia school boards Tuesday; Lakehead, Hastings-Prince Edward and Ottawa-Carleton school boards Wednesday; and Trillium Lakelands, Renfrew and York Region school boards Thursday.

"If you take away people's rights, then it's going to be a lot harder to come to an agreement with them," said NDP MPP Peter Tabuns, who called on Education Minister Laurel Broten to scrap Bill 115. "Perhaps she deserves a detention on this."

Tory MPP Lisa MacLeod said the government has the power under Bill 115 to impose collective agreements and ban strikes, and should be acting to keep kids in class.

The Ontario Conservatives supported the Liberal legislation because otherwise teacher contracts would have automatically rolled over on Aug. 31, 2012, ensuring wage increases the deficit-plagued province couldn't afford, MacLeod said.