Lesson plan

Understanding Prefixes: Dia- and Per-

Show students how knowledge of prefixes can help them determine word meaning. This lesson reviews the prefixes dia- and per- and gives students opportunities to think about how a word’s meaning is related to the prefix.
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Students will learn the meaning of the prefixes dia- and per- and use them to help determine the meaning of unknown words.

(5 minutes)
Playing with Prefixes Dia and Per
  • Write the imaginary words on the board: Predance, Redance, Antidance.
  • Ask students what they notice about the three words. What do they have in common? How are they different? They should notice that all three words have the root “dance” and common prefixes.
  • Have students guess what these words would mean if they were real words.
  • Explain that they just used one of the best strategies to understand the meaning of unknown words: Break the word into parts and use meanings of any word parts to give you clues as to the meaning of the word.
  • Tell students that they are going to learn two new prefixes today that will help them apply this strategy to new words.
(10 minutes)
  • Explain that the prefix DIA means AcrossAnd when it’s added to another word part it makes a word that has something to do with going through.
  • Write this as the first entry on a chart paper titled “Word Parts and Their Meanings” so that students can use it as an ongoing reference.
  • Draw the example of DIAMETER as it is a measurement of the line that goes across the centre of a circle.
  • Explain that the prefix PER means means Through- very similar to DIA. Add this as the next entry on the chart paper.
  • Draw the example of paper that is PERFORATED and show the tiny holes going through that make it easy to tear.
(10 minutes)
  • Having students work in pairs or small groups ask them to generate a list of words that use these two morphemes, DIA and PER. Give 5 minutes to brainstorm.
  • Have groups share a few examples and discuss how each example may or may not have a meaning related to the prefix. For example, perspiration is sweat that comes through your skin to cool you down when you get too hot.
(20 minutes)
  • Provide the worksheet Playing with Prefixes Dia and Per.
  • Instruct students to use their new understanding of the prefixes to work through the examples on the exercise.


  • Have students use the websites listed in the Suggested Media/Books section to interact with words that share these prefixes.


  • Encourage students to explore other Greek and Latin word parts to add to the class chart - or start their own list.
  • Use computers/internet to go to the interactive websites listed above to further explore these and other word parts.
  • Circulate the room as students are working independently and see that their definitions and illustrations accurately show the meaning of the word and prefix.
  • Collect student work if you don’t get to assess everyone during work time.
(5 minutes)
  • Share some examples of student drawings and discuss how the illustrations showed the meaning of “across” or “through.”

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