Ottawa Teachers' Strike

Q120: When will classes in Ottawa elementary schools be cancelled due to labour action?
Before May 31th: 25%
Between June 1st and December 31, 2015: 25%
Not before December 31, 2015: 50%
(This question requires a significant number of schools to stop offering classes; one or two schools would not be sufficient.  The length of the cancellation must be at least one day)

Ottawa elementary school teachers will be beginning the first phase of labour action this week, as part of negotiations with the school board and the province (see article here and here).  If negotiations go poorly, they could decide to strike, leading to class cancellations.

News articles don't give much of a sense about the likelihood and timing of a strike.  My sense is that a strike has about a 50% chance of happening (given the strike by the Durham teachers' union), and it is quite possible that a strike could begin by the end of the month.