Prior knowledge questions

Questions that require you to already know a specific science fact are called prior knowledge questions. These questions are rare, but they can be some of the trickiest ones you’ll see because they don’t depend much on the passage. In many cases, you either know the fact or you don’t.

Here’s an example of a prior knowledge question:

This is the kind of question where outside knowledge matters. If you know what derived units are, you’d likely recognize the answer as D. If you don’t know the topic, the passage probably won’t give you enough information to work it out.

So if the passage won’t help much, how do you handle these questions when they show up?

The key is not to spend your study time trying to memorize a long list of isolated facts. Prior knowledge questions from past tests also aren’t likely to appear again in the exact same form - test writers want them to feel unfamiliar. Instead, the most useful approach is to treat these as inference questions.

Treat prior knowledge questions as inference questions

If you haven’t read the chapter on Inference questions, read that before continuing. You’ll need the problem-solving process from that chapter to understand the approach in this section.

Using that same process, you’ll handle a prior knowledge question the same way you handle an inference question:

• Look for relevant information in the passage.
• Use the answer choices to eliminate what you can.
• Make your best educated guess.

The main difference is that, for prior knowledge questions, you’ll usually find little to nothing in the passage that directly connects to the question or the answer choices.

Spend as much time searching the passage as you would for any other question. That way, you don’t have to stop and decide whether it’s a prior knowledge question - you just follow the process. If you still can’t find support in the passage, make an educated guess based on what you can eliminate.

Common topics for prior knowledge questions

If you’re already comfortable with the science section and the main thing you want to improve is your performance on prior knowledge questions, this subsection can help. Below is a list of common topics that show up in these questions:

Chemistry

• Molecular structures (atoms, protons/neutrons/electrons)

• Phases of matter (solid, liquid, gas, boiling point, freezing point)

• Density (solids are more dense than liquids, liquids are more dense than gasses)

• Unit changes (see [Unit conversions] chapter in Math section of this book)

• Charges (Protons are positive, electrons are negative. Opposite charges attract)

• pH (scale 0-14, 0 is most acidic and 14 is most basic. Water is neutral at 7)

• Molar mass

• Empirical formula

Biology

• Taxonomy (domain, kingdom, phylum, class, order, family, genus, species)

• Genetics (Punnett squares, DNA, genotype/phenotype, gamete)

• Photosynthesis (Plants take in CO₂, water, and sunlight. They produce oxygen and sugar or glucose)

• Cell biology

• Greenhouse gases

• Natural Selection

• Cellular Respiration

Earth Science/Astronomy

• Layers of the earth

• Order of the planets (Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune)

Physics

• Kinetic vs potential energy

• Gravity

• Basic math skills

Focus on these topics only after you’ve practiced the other areas of this guide. This should be one of the last things you study.