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Take the Prefix Challenge!

Lesson Question:

How can students use prefixes to help them transform words' meanings and to decode unfamiliar words?

Applicable Grades:


Lesson Overview:

In this lesson, teams of students compete with one another to find out which team can create the largest number of words by combining a set of prefixes with a set of words—consulting the Visual Thesaurus when they are unsure about their lexical creations.

Length of Lesson:

One hour to one hour and a half

Instructional Objectives:

Students will:

  • use the Visual Thesaurus to analyze how a prefix can transform a word's meaning
  • form words by combining common prefixes with a set of words
  • use the Visual Thesaurus as a reference to verify whether or not a particular prefix can be combined with a particular word, and to define words


  • student notebooks
  • white board
  • computers with Internet access
  • scissors (one pair per small group, optional)
  • "Twelve Common Prefixes" sheets (one per small group) [click here to download]
  • "Twelve Words" sheets (one per small group) [click here to download]
  • "Prefix Word Log" sheets (one per small group) [click here to download]


  • The set of prefixes used for this lesson is a subset of the most frequently used prefixes, as listed in Michael F. Graves's The Vocabulary Book (Figure 5.4 "Twenty Most Frequent Prefixes"—based on research by T.G. White, J. Sowell, and A. Yanagihara).

Prefix Web sites:


Contrasting images associated with active v. inactive:

  • On a projected screen display the Visual Thesaurus word map for the word active and then right-click on the word to "Search for Images." Students will see various images, ranging from exercise programs created for the Wii to a diagram of an active muscle.

  • Repeat this exercise with the word inactive, to display images of people on couches, inactive volcanoes, etc.

  • Briefly discuss this contrast in image displays. What do students think the prefix "in" does to a word? How did adding "in" to active change its meaning?

(Note: if you do not have access to an interactive white board or to a projected screen, you could have half the class draw images for "active" and the other half for "inactive" as visual prompts.)

  • Establish that the prefix in, meaning not, negates the original adjective active—transforming its meaning to its opposite. Explain that there are other similar prefixes that perform the same function (im as in impossible; ir as in irrational; il as in illegal).


Defining prefix and introducing "The Prefix Challenge":

  • Explain that a prefix is a group of letters that has been added to the front of a word, thereby changing the meaning of that word. For example, if you add mid (a prefix meaning middle) to week, the meaning of the word changes to "the middle of the week." (You could also point out that the word prefix itself contains the prefix pre --meaning before--which makes perfect sense when you consider a prefix's position in a word.)
  • Organize the class into small teams of students and explain that they are about to compete with one another in a "prefix challenge"—a competition to see which group can come up with the largest number of words formed by combining a set of twelve prefixes with a set of twelve words.
  • Take a few minutes and review the twelve prefixes on the "Twelve Prefixes" sheet and their most common meanings:

un- (not)

trans- (across)

inter- (between)

re- (again)

pre- (before)

fore- (before)

semi- (half)

de- (undo)

over- (excessively)

dis- (not)

mis- (wrongly)

sub- (under)

  • Distribute to each team a "Twelve Common Prefixes" sheet, a "Twelve Words" sheet, and a "Prefix Word Log" sheet. (Note: if you have scissors available, it would be ideal for students to cut each prefix and word out so that they can manipulate these as movable word part cards.)
  • Give students a set amount of time (perhaps ten to fifteen minutes) to combine the twelve prefixes and twelve words to create as many words as they can during that time. Students must enter the words they create on to their "Prefix Word Log" sheets, along with their Visual Thesaurus definitions.
  • Emphasize that each word they enter on their team's Word Log sheet must be found on the Visual Thesaurus and must also make use of the legitimate prefix—as defined on the prefix sheet. For example, students may try to create display as a combination of the prefix dis and the word play; however, even though display is a word—it is not the sum of the parts dis (as in not) and the word play.


Declaring a winner and sharing word combinations:

  • At the end of the allotted time period for the Prefix Challenge, declare a winning team based on how many words they formed by combining the twelve prefixes with the twelve words. Then, have the winning team members take turns sharing the words they formed and their definitions. (Here are some of the more obvious combinations: replay, mislead, foretell, prehistoric, subtitle, overpay, unable, transnational, decode, interstate, disrespect, semicircle.)
  • As the winning team recites their words and definitions, other students should check to see if they listed the same words on their "Prefix Word Logs." What combinations did they miss? What combinations did they include that the winning team neglected?
  • Emphasize that even though some prefixes may have the same meanings (i.e., pre and fore both mean "before"; un and dis both mean "not"), they are not interchangeable. For instance, you can form the word disrespect but not unrespect! In addition, words with multiple meanings can combine with prefixes in different ways: the verb to state can be transformed to restate or overstate by adding prefixes re and over, while the noun state can become interstate by adding the prefix inter.
  • Also point out that adding a prefix can sometimes alter a word's part of speech. For instance, adding dis to the adjective able creates a verb: to disable.

Extending the Lesson:

  • If time permits in class or for homework, you could send students on a prefix scavenger hunt. Students could search a class text (perhaps a novel or story the whole class is reading) or use any text they can find (newspapers, magazines, street signs, etc.) to see who can find the most words containing the prefixes introduced in this lesson. Then, they can add them to a "Prefix Word Log" sheet like the one used in this lesson.


  • Assess teams' "Prefix Word Log" sheets to verify that their entries contain words formed by combining the prefixes and words introduced in this lesson.
  • Assess teams' "Prefix Word Log" sheets to verify that their entries contain accurate definitions for the "new words."
  • Students' mastery of this set of twelve prefixes could easily be assessed by quizzing students on the meanings of additional words that contain these prefixes.

Educational Standards:

Language Arts

Standard 5. Uses the general skills and strategies of the reading process

Level II (Grade: 3-5)

Uses phonetic and structural analysis techniques, syntactic structure, and semantic context to decode unknown words (e.g., vowel patterns, complex word families, syllabication, root words, affixes)

Level III (Grade: 6-8)

Uses word origins and derivations to understand word meaning (e.g., Latin and Greek roots and affixes, meanings of foreign words frequently used in the English language, historical influences on English word meanings)

Level IV (Grade: 9-12)

Extends general and specialized reading vocabulary (e.g., interprets the meaning of codes, symbols, abbreviations, and acronyms; uses Latin, Greek, Anglo-Saxon roots and affixes to infer meaning; understands subject-area terminology; understands word relationships, such as analogies or synonyms and antonyms; uses cognates; understands allusions to mythology and other literature; understands connotative and denotative meanings)

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