Substitute
Substitute
[In a classroom, the board says "Math" on the top-left corner, and "Mr. Munroe" in the middle. A Cueball portrays Randall, standing in front of it, speaking to the class.] Randall: Miss Lenhart couldn't be here today, so she asked me to substitute. Randall: I've put out your tests. Please get started.
[A student in the first row raises the exam paper and says:] Student: Mr. Munroe, Miss Lenhart never taught us this.
Randall: That's because Miss Lenhart doesn't understand how important certain kinds of math are. Student: But this just looks-- Randall: This material is more vital than anything you've ever learned Student: But-- Randall: No buts.
Randall: This is a matter of life and death.
[Excerpt from the exam paper.] Name: _________
[A stick figure is standing, hands over head. A velociraptor is running towards it.]
1. The velociraptor spots you 40 meters away and attacks, accelerating at 4 m/s^2 to its top speed of 25 m/s. When it spots you, you begin to flee, quickly reaching your top speed of 6 m/s. How far can you get before you're caught and devoured?
2. You're at the center of a 20m equilateral triangle with a raptor at each corner. The top raptor has a wounded leg and is limited to a top speed of 10 m/s.
[A stick figure is shown in the above situation. The picture has a legend " (Not to scale). "]
The raptors will run toward you. At what angle should you run to maximize the time you stay alive?
3. Raptors can open doors, but they are slowed by them. Using the floor plan on the next page, plot a route through the building, assuming raptors take 5 minutes to open the first door and halve the time for each subsequent door. Remember, raptors run at 10 m/s and they do not know fear.

This comic refers to the film Jurassic Park , a 1993 movie based on the 1990 novel by Michael Crichton . The film centers around a billionaire who bought an island and opened a zoo or theme park for dinosaurs that he has cloned from DNA recovered from blood found in fossilized mosquitoes. After a computer programmer shuts down the security systems to steal embryos for a rival company, several of the creatures, among which are the Velociraptors subject of this comic, run loose and try to devour every human in the theme park.
Velociraptors (often shortened to "raptors") are a species of relatively small, carnivorous dinosaur that play a central role in the original film, as well as its sequels. In the film, packs of Velociraptors antagonize the main characters at various points, even entering buildings. According to newer researches, the Velociraptors in the film were erroneously based on the Utahraptor species of dinosaur. Unlike the movie, in which they are depicted as having a reptilian skin, both species of dinosaur in reality are theorized to have been feathered. The word "raptor" also refers to modern birds of prey .
Randall is asked to substitute for Miss Lenhart in math class. The first page of the test he devises contains three questions, which have the recurring theme of humans running from said velociraptors. For the answers, see the trivia section. As Randall says in the comic: "This material is more vital than anything you've ever learned," the joke being that Randall is somehow fearful that such a thing could happen.
Velociraptors, and in particular, the irrational fear of being attacked by them in the modern world, appear several times in xkcd . This is the second such instance; the first is 87: Velociraptors
In the title text, Randall asks the kids whether they find this possibility humorous (and they rightfully should, considering that the chances of such a thing occuring are astronomically low).
[In a classroom, the board says "Math" on the top-left corner, and "Mr. Munroe" in the middle. A Cueball portrays Randall, standing in front of it, speaking to the class.] Randall: Miss Lenhart couldn't be here today, so she asked me to substitute. Randall: I've put out your tests. Please get started.
[A student in the first row raises the exam paper and says:] Student: Mr. Munroe, Miss Lenhart never taught us this.
Randall: That's because Miss Lenhart doesn't understand how important certain kinds of math are. Student: But this just looks-- Randall: This material is more vital than anything you've ever learned Student: But-- Randall: No buts.
Randall: This is a matter of life and death.
[Excerpt from the exam paper.] Name: _________
[A stick figure is standing, hands over head. A velociraptor is running towards it.]
1. The velociraptor spots you 40 meters away and attacks, accelerating at 4 m/s^2 to its top speed of 25 m/s. When it spots you, you begin to flee, quickly reaching your top speed of 6 m/s. How far can you get before you're caught and devoured?
2. You're at the center of a 20m equilateral triangle with a raptor at each corner. The top raptor has a wounded leg and is limited to a top speed of 10 m/s.
[A stick figure is shown in the above situation. The picture has a legend " (Not to scale). "]
The raptors will run toward you. At what angle should you run to maximize the time you stay alive?
3. Raptors can open doors, but they are slowed by them. Using the floor plan on the next page, plot a route through the building, assuming raptors take 5 minutes to open the first door and halve the time for each subsequent door. Remember, raptors run at 10 m/s and they do not know fear.
