School Reunion 2.4
The Doctor (#10, Tennant) is called to go deep under cover in a high school where something cosmic is afoot. He disguises himself as Mr. Smith, a physics teacher (which results in the adorable “Physics, physics, physics” lecture) to get to the bottom of the mystery of the eaten children and why the kids know so much, like how to travel faster than the speed of light. Naturally, it turns out that the teachers, led by Mr. Finch (Anthony Stewart Head), are the ones gobbling up the students because they are actually giant bats called Krillitanes using children to crack a computer code so that they can control the building blocks of the universe.
Meanwhile, Rose Tyler and Mickey Smith, who had alerted the Doctor to the suspicious activities of Deffrey Vale High School, meet the Doctor’s former companion, Sarah Jane Smith (the late Elisabeth Sladen), who is also under cover as a journalist, along with her metallic dog K9 (formerly the Doctor’s dog). As the Krillitanes get closer to cracking their “God code,” Mickey crashes his car through the school and unplugs the hypnotic computers so the kids can go free. Mr. Finch is defeated by K9’s sacrifice–he lasers the toxic oil the aliens have been using in the cafeteria french fries–but don’t worry, the Doctor makes sure K9 is well again before he departs.
In the end, it’s really about the dynamics between Doctor and companions, with Rose essentially seeing her future self in Sara Jane, practically abandoned by the Doctor, and understanding she is part of a lineage of companions and not unique, whereas to her boyfriend Mickey, she is special.
The Caretaker 8.6
The Doctor (#12, Capaldi) is called to go deep under cover in a high school where something cosmic is afoot. He disguises himself as Mr Smith, the school caretaker, (which results in all sorts of quirky janitor moments like showing off his TARDIS to a student) to destroy the Blitzer, a soldier droid brought down by its own dependence on following orders. This is a direct parallel to the Doctor’s mistrust of Danny, Clara’s new boyfriend, who used to be a soldier…which is in itself an echo of the way #10 felt for Rory. #10 had always preferred Amy’s more handsome friend and didn’t understand why she’d settle for Rory. Likewise, #12 prefers the literature teacher who looks, speaks, and dresses like Matt Smith and doesn’t understand why she’d settle for Danny, who he’s convinced must be a PE teacher, rather than the maths teacher he really is. Look out, Sherlock fans, Moffat played the same card with Molly’s fiance.
The Doctor, Clara, and Danny are able to defeat the Blitzer with tech–some little explosives; the sonic screwdriver, which apparently has a setting #41 that means it can just go in and solve whatever problems the writers can’t figure out how to fix; and an invisibility watch, because we’re going to need a new magic watch after the Doctor apparently gave Elisabeth Sladen’s widower his pocket watch earlier this season.
In the end, it’s really all about the fatherly figure of the Doctor learning to accept Danny as good enough for Clara for whom he holds the highest standards.