Teacher: In this task, you are given a question and a context passage. You have to answer the question based on the given passage.
Teacher: Now, understand the problem? If you are still confused, see the following example:
what is the first event mentioned?, Context: The Russian Revolution is the series of revolutions in Russia in 1917, which destroyed the Tsarist autocracy and led to the creation of the Soviet Union. Following the abdication of Nicholas II of Russia, the Russian Provisional Government was established. In October 1917, a red faction revolution occurred in which the Red Guard, armed groups of workers and deserting soldiers directed by the Bolshevik Party, seized control of Saint Petersburg (then known as Petrograd) and began an immediate armed takeover of cities and villages throughout the former Russian Empire.
Solution: Russian Revolution
Reason: This is a good example, and the Russian Revolution is the first event mentioned.

Now, solve this instance: How many times did the players stage a work stoppage?, Context: The NFL Network ceased airing Arena Football League games partway through the 2012 season as a result of ongoing labor problems within the league. Briefly, the games were broadcast on a tape delay to prevent the embarrassment that would result should the players stage a work stoppage immediately prior to a scheduled broadcast. (In at least once incidence this actually happened, resulting in a non-competitive game being played with replacement players, and further such incidents were threatened.) Once the labor issues were resolved, the NFL Network resumed the practice of broadcasting a live Friday night game. NFL Network dropped the league at the end of the 2012 season.
Student:
at least once