Learning the analysis of electrical circuits represented by circuit diagrams is often challenging for novice students. An open research question in electrical circuit analysis instruction is whether color coding of the mathematical symbols (variables) that denote electrical quantities can improve circuit analysis learning. The present study compared two groups of high school students undergoing their first introductory learning of electrical circuit analysis. One group learned with circuit variables in black font. The other group learned with colored circuit variables, with blue font indicating variables related to voltage, red font indicating those related to current, and black font indicating those related to resistance. The color group achieved significantly higher post-test scores, gave higher ratings for liking the instruction and finding it helpful, and had lower ratings of cognitive load than the black-font group. These results indicate that color coding of the notations for quantities in electrical circuit diagrams aids the circuit analysis learning of novice students.