The SAT Prep Black Book

SAT Math

Special Math Technique: Learning From Diagrams

Many math questions on the SAT will involve diagrams. You probably already knew that. But you might not know that SAT diagrams can actually give away a lot of information about the best ways to attack a particular question.

When an SAT diagram is drawn to scale, you can often extract important information from it just by looking at it. For example, you can eyeball the relative sizes of angles and the relative lengths of line segments.

But when a diagram isn’t drawn to scale—or simply isn’t provided at all—you can often learn even more.

When the College Board decides to leave out a diagram or to include a diagram that isn’t drawn to scale, they make this decision because including an accurate diagram would give away the answer to the question you’re being asked. In these situations, it’s often helpful to try to draw your own scaled diagram in the test booklet if you can.

Similarly, the College Board will sometimes show you a diagram and then provide a further explanation of that diagram in the written portion of the question. Again, the reason for this is simple: If the written information had been labeled directly on the diagram in the first place, the answer to the question would have been a lot easier to figure out.

So if you want to maximize your score on the SAT Math section, you’re going to need to practice using diagrams. Whenever you see a diagram on the test, be very alert to the things that are left out of it. Always be prepared to augment the given diagram (or provide a substitute diagram of your own). You may be surprised at how many questions become much, much easier once you catch on to this.