ET has an exclusive look at the filming of 'When I Kissed the Teacher,' with Lily James (who plays Meryl Streep's younger self).
"We start Mamma Mia! Here We Go Again with the song, 'When I Kissed the Teacher,'" Lily James, who plays the younger version of Meryl Streep's character, Donna, explains in this behind-the-scenes look at the filming of the musical number, a track off Abba's 1976 album, Arrival.
Here We Go Again is both a sequel and a prequel to the original Mamma Mia!, picking up in Greece 10 years later with the news that Donna's daughter (Amanda Seyfried) is pregnant, but also bouncing back in time to learn how Donna and her best bandmates came to form The Dynamos. This scene is essentially their origin story, taking place during graduation from Oxford in '79 and featuring disco boots, striped jumpsuits and feathered boas.
"'When I Kissed the Teacher' gives us a really great springboard into this theme of girl power," Jessica Keenan Wynn, who plays young Tanya (Christine Baranski), adds, while Alexa Davis, who plays young Rosie (Julie Walters) says, "This is the first number you see in the film and it's such a big moment for us to establish these girls and make sure you are on the same vibe that we're on for the rest of the film."
Watch the lyric video for the full number below:
Watch the trailer for Mamma Mia! Here We Go Again:
Mamma Mia! Here We Go Again opens in theaters on July 20. Meanwhile, moms will be treated to a free sing-along screening of Mamma Mia! on Mother's Day. Select theaters across the country will be hosting screenings -- and debuting exclusive new footage from the sequel -- on Sunday at 10:00 a.m. (For tickets and a list of theaters, go here.)