Liberal with production stills for “Glee’”s milestone 100th episode, FOX was surprisingly conservative when it came to sharing behind-the-scenes photos from the filming process.

It did, however, share a look at a scene that features past and present WMHS students collectively performing.

Airing March 18, the episode could serve as the final “milestone” moment before “Glee” airs its series finale next year. FOX’s official description is as follows:

Current and past members of New Directions reunite for one final assignment – to reinvent their favorite performances. But these new versions of the series’ most iconic tracks should not be seen as goodbye to glee club. On the contrary, they are celebrations of what the club has meant to each and every member.

The behind-the-scene gallery follows. Click the thumbnails for the full images:

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