As the children from two different schools start to argue and fight, the duo have to split them up, before explaining the procedure and what it will mean for each of them.
You can watch the full clip right above now.
Elsewhere in Sunday's (28th January) episode, everyone in Poplar is excited about the imminent Moon landing, with a public showing taking place outside.
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Sister Monica Joan is thankful to be able to witness a Moon landing in her lifetime, and finds herself overcome with emotion when Neil Armstrong steps onto the Moon’s surface.
Series creator and writer Heidi Thomas previously told Radio Times magazine that the monumental event will see the characters grappling with existential questions, explaining: "Newcomers Joyce and Rosalind arrive with much to learn. As 1969 unfolds, we’ll see change and challenge rock the world of our beloved nuns, nurses, medics and midwives.
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"Even as man prepares to walk on the Moon, we see them grappling with life’s eternal questions. Who are we? What is love? And where do we belong?"
Another storyline in Sunday's episode will see the pupil midwives undergoing a review. Following this, Joyce is assigned to Prue Stanton, a rumbustious warm-hearted local, under Trixie's tutelage - however, things take a turn for the worse when Trixie makes a serious mistake.
Call the Midwife airs on BBC One on Sundays. If you're looking for more to watch, check out our TV Guide and Streaming Guide or visit our Drama hub for more news and features.
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