Understanding Pencil Usage in Exams

The video explains why number 2 pencils are traditionally used in exams, tracing the history of automated test scoring from Reynold Johnson's invention in 1931 to modern optical mark-sensing machines. It highlights the role of graphite in pencils, which is conductive and blocks light, making it ideal for early scoring machines. The video also discusses the evolution of pencil grades and how modern machines can detect various marks, though number 2 pencils remain a safe choice for exams. The video concludes with a call to support SciShow on Patreon.

Why are students often instructed to use a number 2 pencil during exams?

• Because it is the cheapest pencil available.

• Because it is the only pencil that machines can read accurately.

• Because it is a tradition passed down from ancient times.

• Because it is the only pencil that can write on exam paper.

Who invented the first automatic test scoring machine?

• Nikola Tesla

• Thomas Edison

• Reynold Johnson

• Alexander Graham Bell

What material in pencils is electrically conductive and used in scoring machines?

• Graphite

• Lead

• Ink

• Clay

What was the primary function of the phototubes in the next generation of scoring machines?

• To detect light

• To detect sound

• To detect temperature

• To detect pressure

Why is graphite preferred over ink for optical mark-sensing machines?

• Graphite is easier to produce than ink.

• Graphite is cheaper than ink.

• Graphite is more colorful than ink.

• Graphite blocks light better than many inks.

What does the 'HB' label on pencils stand for internationally?

• High Black

• Hard Bold

• Heavy Black

• Hard Black

What is the main reason number 2 pencils are recommended for exams?

• They are the most durable.

• They are the most affordable.

• They make marks that are dark enough to be sensed but light enough to be erased.

• They are the most environmentally friendly.

What is the role of clay in pencils?

• To make the pencil waterproof

• To make the pencil lighter

• To make the pencil colorful

• To hold the graphite together and control its hardness

How have modern scoring machines improved compared to older versions?

• They require manual scoring.

• They can detect almost any kind of mark within the bubbles.

• They can only detect number 2 pencil marks.

• They are slower than older machines.

What is a safe practice to follow when taking standardized tests like the SATs?

• Use any pencil you like.

• Use a pen for better visibility.

• Use a mechanical pencil.

• Bring a couple of number 2 pencils.