As far as who to vote for, it's as easy as ABC - Anyone But Conservative (also, visit NiagaraVotes2011.ca). The last Conservative governments we had in Ontario were not teacher-friendly at all. Teachers ended up walking picket lines for two weeks in 1997, the government introduced the Ontario Teacher Qualifying Test (since replaced by NTIP), and introduced teacher re-certification that required teachers to complete a number of professional learning courses every five years to maintain their teaching certification. Education funding was also cut resulting in fewer specialist teachers in schools and larger class sizes. Slashed budgets combined with tax cuts (decreasing government revenue) left little room for education. Meanwhile, the Conservatives took money out of the classroom by funneling it into the EQAO (Education Quality and Accountability Office) and LNS (Literacy and Numeracy Secretariat) standardized testing regimes. Private school tax credits were also introduced, taking more money out of public schools.
Tim Hudak (the leader of the Ontario Progressive Conservatives) was a Cabinet Minister during those previous Conservative governments under Premier Mike Harris. Ideas for things such as merit pay for teachers (likely based on standardized testing scores as is done in the U.S.) have already been floated, and you should not expect a Hudak government to be good for teachers or students.
Refuse to Vote Against Kids
Ontario NDP election platform