The TOEFL draws from a predictable set of academic domains: natural science, social science, arts, and campus life. Studying vocabulary by topic is far more efficient than learning random word lists.
ETS's official TOEFL guide shows that reading passages come from university-level textbooks. When you study words grouped by subject, you build the mental frameworks that help you process these passages quickly.
For example, science passages frequently use words like hypothesis (a proposed explanation), corroborate (to confirm with evidence), and empirical (based on observation or experiment). Learning these together creates a cluster — when you see one, the others come to mind, helping you navigate the full passage.
Here's a practical system: create topic-based word groups. Under "Research Methods," collect words like hypothesis, methodology, empirical, variable, correlation. Under "History," gather words like era, revolution, precedent, legacy, reform.
Aim for 5-7 topic clusters with 10-15 words each. Review one cluster per day, cycling through all of them each week. This mirrors how the TOEFL actually tests you — a passage about climate research will use climate vocabulary, not random GRE words.
Building topic-based vocabulary doesn't just help with reading — it directly improves your TOEFL Writing and Speaking scores too. When you can use precise academic vocabulary in your responses, you demonstrate the English proficiency that earns higher scores.