Use of color is a tremendous memory aid and I begin the use of color to aid memory in the Colonial Era. From fifth grade through high school I have used map work in which students color New England colonies red for "first Patriot blood spilled," Middle Colonies yellow for "Breadbasket" grain production, and Southern Colonies green for fertile coastal plains prior to introducing the "Colonial Sorting Activity." I then encourage them to highlight or underline their notes on each of the colonial regions in the corresponding color. My APUSH students often said how during the May exam they closed their eyes, envisioned the map and instantly recalled the data (facts, events, cause/effect) they needed to answer the question or essay.
Consistent use of color is a great memory tool and I follow up the colonial color scheme with this one in which students highlight notes according to PERMS (Political, Economic, Religious, Military, and Social) cause/effect in these colors shown in the attached file. Map colors work as well as highlighters. You can even elicit the appropriate color from students through questioning:
If we were to highlight our social notes, what color would you use? (Students invariably answer yellow or orange.)
And so forth.
As students review for the AP Exam or summative exams, color coded notes reflecting PERMS (which I first introduce as SPERM b/c students never forget that acronym!) is a great way to sort and review notes by theme as well as chronology. Just think how easy it would be for students to recall factual data concerning the economic business cycle over the eras if those notes were highlighted in green (for money).
Trust me this works.