Chekhovs Classroom / Live-Action Films

• In 21 Jump Street, Jenko uses his newfound chemistry expertise to improvise a bomb.
• Black Death has the method of mercy-killing.
• Elwood Blues goes on one of these lectures to his brother in The Blues Brothers on the benefits of a cop car: cop shocks, engine, suspension, etc. This comes in handy with the utter vehicular chaos that ensues.
• In Copycat, Sigourney Weaver's character gives a lecture on serial killers and at one point asks all the men in the audience to stand. Several of the men's faces are then projected on the screen behind her as she explains that men are more likely to be serial killers, and how they look just like everybody else. Naturally, the movie's villain (a serial killer himself) is one of the men projected on the screen. Additionally, she then goes on to list the names of several infamous serial killers — the villain then goes out to kill his victims one at a time using the modus operandi of each of the serial killers she mentions in order.
• The Devil's Backbone has a borderline example: in one scene, the boys are in class learning about prehistoric man, and Carmen shows them a picture of hunters taking down a mammoth as a group. The image is invoked at the end, when the boys bring down Jacinto by stabbing the crap out of him with sharpened sticks, before shoving him into the well for Santi.
• Easy A was in a way a play on this trope - it even lampshades "how the book you read in class seems to be weirdly related to your life", as part of the heroine's general Genre savviness.
  • In the same scene, the heroine says in an after thought that this possible for most books, except for Adventures of Huckleberry Finn. Turns out she was was wrong, when the movie's Pet Homosexual runs away from home with his African-American boyfriend. This causes Olive, the heroine, to apologize to Mark Twain.
• The titular character of Fresh, while suffering a Heroic BSoD after his would-be girlfriend was killed when an Ax-Crazy gangster shot up the playground when he was losing at basketball, gets berated by his father who only notices how poor his son's chess game is. Still, the chess lessons on the importance of exploiting your opponent's character and sacrificing any game piece if it means winning come in quite handy when Fresh enacts his plan to escape his neighbourhood by manipulating the gangsters to kill each other, then turning in the survivors to the police and applying for witness protection, while relying on being Just a Kid to stay Beneath Suspicion.
• Green for Danger: When introduced, Dr. White is giving a lecture to the doctors about the new efficiency measures he has introduced since taking over as hospital administrator, including repainting the bins marked 'WASTE' to say 'SALVAGE'. This is an Establishing Character Moment, but later becomes significant because it explains where the murderer got the paint they used to disguise the carbon dioxide cylinder as an oxygen cylinder.
• The Hunger Games: Haymitch tells Peeta not to start a fire as it's a good way to get killed. Later in the film a girl does just that and you can guess the outcome. Katniss and Rue then exploit this with decoy fires in a bid to destroy the career alliance's stockpile.
• Indiana Jones and the Last Crusade. Early on, Indy mentions in class that there is no buried treasure, X "never marks the spot", and archaeology is about facts, not truth. The entire movie is a subversion of this lecture: there was buried treasure (the Grail, along with many, many other artifacts that any real-world archaeologist would deem significant); X did in fact mark the spot (as the Roman numeral X); and archaeology did help Indy discover truth as well as fact (the scene where Indy is confronted by the Grail Knight and later reconciles with his father). Although Indy was right about one thing: most of the actual archaeology done in the movie was done in (or under) a library.
• Dr. Crowley demonstrates the explosive properties of sodium in the first classroom scene of Jack Brooks: Monster Slayer. Of course, it comes in handy against the final monster...
• Jett Jackson: The Movie, the made-for-TV movie of The Famous Jett Jackson: After Jett and his TV character Silverstone have switched places in each other's universes and have been living in each other's shoes for a while, Jett's grandmother later approaches Silverstone in a quiet moment, where it's revealed that she'd already figured out he wasn't her grandson. When Silverstone asks how she knew, she explains that when Jett was born, she looked him in the eyes and knew that from thenceforth she'd always be able to know and identify him. In the climax of the film, the shape-shifting Big Bad in Silverstone's world makes himself look like Jett, causing a doppleganger problem when the three confront one another; Jett and Silverstone look each other in the eye and know they're both the real deal.
• King Ralph could practically be the naming of this trope. At the end, when Ralph is looking for a way out, he tells an aide that while he usually ignores what the aide says, that aide once said, 'I think we made the right choice'. Ralph remembers that and asks who the other candidate is, and the denouement begins.
• The film Knowing has Nicholas Cage giving a class a lecture early on about the composition and nature of the sun. The third act becomes about solar flares wiping out everyone on the surface of the planet. Pointedly, however, the knowledge did not save the Earth.
• In Lone Star State of Mind, Earl and Jimbo, taking a page from an action movie they had watched earlier, defeat some thugs by throwing a cell phone into the air and rushing them when they look up. Subverted later: Junior tries to imitate this trick, but prematurely congratulates himself on being "clever" and forgets to rush his opponent as the cell phone falls uselessly.
• In Mean Girls Cady uses this to win the Mathletes competition. She harks back to an old maths class to answer a question about limits.
• A variation occurs in Monty Python and the Holy Grail: at the beginning, a castle guard gets distracted by King Arthur's "coconut horse" and ends up talking at great length about whether swallows could carry coconuts into England. Toward the end of the film, the Bridgekeeper asks, "What is the air-speed velocity of an unladen swallow?" Arthur remembers a detail discussed by the original guard and asks, "What do you mean? An African or European swallow?" which causes the Bridgekeeper to fall into his own trap. In the original ending, which was cut at the last minute, the English army was saved by sparrows dropping coconuts on the French.
• In Napoléon, the geography lesson about the climates of islands that mentions Saint Helena was presumably intended this way. As the sequels never got made, it remains an Orphaned Setup.
• Mr. Bruner points this out in Percy's Greek History class in Percy Jackson and the Olympians before he realizes he's a demigod. Then it goes to to the extreme when he goes to Camp Half Blood. Then later, Annabeth uses her non-demigod knowledge in a Sphinx trial, except she gets fed up with the fact that the questions aren't riddles, and screws everything up.
• In Poker Night, almost all of the lessons imparted by the senior detectives come into play as Jeter escapes except asking for a kiss.
• In Rovdyr, Mia insists on going over the rules for back country hiking with her friends in the van. She doesn't get much past the first one—that red ribbons on trees mark the way back to the road—but that is the one that becomes important later in the film.
• In Shorts, Helvetica does her science projects on female wasps and their habit of "male-stuffing". Later on, in the fight against Giant Mecha Mr. Black, Helvetica uses the rainbow wishing rock to wish that she were a giant wasp... male-stuffing.
• You'd think that in a Superhero School, this would be the case. But in Sky High (2005), it's actually subverted for the main character. Played straight for everyone else.
• Slumdog Millionaire uses a justified version of this trope to great effect. The entire plot is centered on the protagonist explaining episodes in his life that have given him unexpectedly useful knowledge.
• Star Trek: First Contact: Picard's plan in the battle on Deck 16 is to rupture one of the coolant tanks by the warp core, flooding Engineering with the corrosive materials inside and destroying the Collective that the Borg have established there. This plan is repelled by the Borg before Picard's team even gets inside Engineering, but breaking one of the coolant tanks is how Data finally defeats the Borg in the climax of the film.
• Starship Troopers has Sergeant Zim demonstrate the importance of combat knives despite it being a 'nuke fight', citing, "The enemy cannot push a button if you disable his hand!" This comes in handy later when Carmen cuts off the Brain Bug's brain-sucking proboscis with a concealed combat knife. Interestingly enough, she wasn't actually at that lecture, being a fleet pilot and all.
  • Worth noting, she was at the lab class where they dissected bugs, causing her Vomit Indiscretion Shot. She seemed to get the hang of using a knife on bugs later on, didn't she?
  • An Anvilicious non-science version also happens with Raczak's high school lecture about the difference between a Civilian and a Citizen. Rico, Carmen and Dizzy are present for that scene early on, and just before the film's final act, the three are together again, where Rico talks about the difference between a Civilian and a Citizen while he and Carmen attend Dizzy's funeral. A Citizen is willing and prepared to sacrifice themself for the good of society, while a Civilian is not.
• Timeline begins with a history lesson for the archeologists. They go back in time and need to use exactly what they just learned.
• X-Men Film Series:
  • In the DVD extras of X-Men, the young mutants are learning about ancient Rome. Rome started out persecuting Christians, and then wound up becoming a Christian empire. How did this happen? "The Emperor became a Christian!" Which is exactly what Magneto had in mind with his plan to turn all the world leaders into mutants.
  • Xavier reading from the thesis on the Cro-Magnons wiping out the Neanderthals in X-Men: First Class. Erik cites it when the US and Soviet fleets turn on them.

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