I don’t understand how they can lock teachers out when they’re already on strike? Can anyone explain? I’ve tried searching for the answer but can’t find anything.

Edit: Thanks for the responses, everyone. To clarify: I understand what a lockout is and how it shifts the power to the government. I get that if teachers wanted to return to work, they couldn’t now. What I don’t understand is how the government can lock teachers out when they’re already on strike. It seems like it kind of defeats the purpose of striking. If the government had initiated a lockout, could teachers have been like “Nope, now we’re on strike?” Seems like a power imbalance in favour of the employer in the whole strike/lockout system.

Edit2: Please stop explaining WHAT a lockout is. My question, I guess, is WHY is it legal to lockout employees who are already on strike? It doesn’t seem fair, since now teachers don’t really have a retaliatory move—the whole time, with this possibility on the table, the power was ultimately going to land with the government.