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You probably learn a lot of physics and chemistry from videos and diagrams. Richard Mayer, a psychologist at the University of California, Santa Barbara (Mayer, 2010), has spent years testing which ways of combining words and pictures help people understand, and which ways get in the way. His principles were written for people who design lessons, but most of them translate directly into how you watch and take notes.
What is the theory behind Mayer's principles?
In a 2003 paper with Roxana Moreno, "Nine Ways to Reduce Cognitive Load in Multimedia Learning", Mayer set out three assumptions:
Two channels. We process pictures and words in separate systems.
Limited capacity. Each channel can handle only a little at a time.
Active processing. Real learning means building connections between the words and the pictures.
When a lesson asks for more processing than you have room for, you are overloaded and learning drops. In a 2010 review for medical educators, Mayer grouped his advice under three goals: reduce extraneous processing (effort that does not serve the lesson), manage essential processing (effort needed to hold the core material), and foster generative processing (effort spent making sense of it). His 2008 article in *American Psychologist* presented 10 evidence-based design principles.
Which principles matter most for a student?
The Norwegian University of Science and Technology's video project lists the principles from Mayer's book *Multimedia Learning*. Here are the ones you can act on yourself, with what each says:
Coherence: people learn better when extraneous words, pictures and sounds are left out.
Signalling: people learn better when cues show how the material is organised.
Spatial contiguity: people learn better when words sit near the parts of the picture they describe.
Segmenting: people learn better from a lesson in learner-paced segments than as one continuous stream.
Pre-training: people learn better when they already know the names and characteristics of the main concepts.
Multimedia: people learn better from words and pictures than from words alone.
Redundancy: people learn better from animation plus narration than from animation, narration and on-screen text together.
The same list includes an individual-differences principle: these design effects are stronger for learners with low prior knowledge. In other words, the newer a topic is to you, the more these choices matter.
Does it work outside the lab?
One test came from a real classroom. Issa and colleagues (2013), with Mayer as a co-author, compared two cohorts of third-year medical students. One cohort of 37 saw a standard bullet-point lecture on shock; another cohort of 43 saw the same content on slides redesigned using Mayer's principles. The redesigned group scored higher on transfer tests one week later (d = 0.83) and four weeks later (d = 1.17). This was a single school with two cohorts rather than randomly assigned students, so treat it as encouraging rather than final.
A 5-step routine for a physics video lecture
Use this on your next 30-minute video, say on electrostatics.
Pre-train (3 minutes). Before you press play, write the five key terms from the chapter heading with a one-line meaning each: field, potential, equipotential surface, flux, dipole. If you cannot define one, look it up first.
Remove extras. Close other tabs and put your phone away. The coherence principle is about the lesson's content, but the same logic applies to anything else competing for your eyes.
Segment. Pause at the end of each idea, roughly every 5 to 8 minutes, and write one sentence on what was just shown.
Draw with labels on the figure. When the lecturer draws field lines, copy the diagram and write the labels on it, next to the lines and charges, instead of in a separate list below.
Explain it back (5 minutes). After the video, cover your notes and explain the main diagram aloud. This is the generative step: you are building the connections yourself.
On captions: the redundancy principle concerns identical text competing with a diagram for your eyes. If captions help you follow an unfamiliar accent or language, keep them on.
If you study with videos often, our guide to learning from video lectures covers pausing, predicting and playback speed, and the learning styles myth explains why "I'm a visual learner" is not the right question.
When a static diagram is not enough, the Fermi Simulation Lab has interactive simulations for ideas that are easier to see than to read. Fermi Courses pair lectures with an AI tutor available on every lecture, so you can stop at a segment and ask about it.
