Year 2 Lesson Plan 24 - Volumes, Absolute Values

This lesson is meant to be the last lesson. If your curriculum has room for 25 lessons, then this should be the last one. Teach lesson 25 first, and then use this as the last lesson. It is a review of vocabulary and a brief exercise in volumes and absolute values (both easy concepts.)
  1. (5 min) Mental Math
    1. What is the square root of 36? [6]
    2. What is square root of 49? [7]
    3. What is square root of 81? [9]
    4. What is cube root of 8? [2]
    5. What is cube root of 27? [3]


  2. (10 min) VOLUMES
    To calculate the volume of a 3-dimensional geometrical solid, find the area of the base and multiply by its height. Volumes are expressed in cubic units. Here are some formulas for volumes:
    • Rectangular prism (a box): volume = length x width x height
      Example: A box that is 3 by 4 by 5 feet has a volume of 60 cu ft.
    • Cube whose side has length S: S x S x S
      Example: A cube whose side is 3 inches long: volume = 27 cu in.
    • Cylinder: volume = base x height = pi x r2 x h
      Example: Radius = 2, height = 5, volume = 20 pi or 62.8
    • Triangular prism: volume = base x height = (length x width/2) x height
      Example: Length = 2, width = 3, height = 4, volume = 12


  3. ABSOLUTE VALUES
    Absolute value is the positive value of a number. It is written with straight bars on each side: | - 6 | = 6 and also | 6 | = 6.
    For x = - 5, | x | = 5
    Why is this important? Well it gives us the size of a number without worrying about its sign. It is useful in calculating distance from point A to point B when point B is smaller than point A.

  4. In-class exercise. No homework this week. This is the last week!

  5. MATH JEOPARDY
    This week's competition is Math Jeopardy. You play it with the class using the rules of jeopardy. This game is a change of pace and gives the kids some interesting practice on vocabulary. If they do not know a word, explain it to them as you go. You can explain the answers, too as you go along for missed questions.

    Questions are worth a variable number of candies (M&Ms, Reese's Pieces or Skittles) . 1-5 candies for jeopardy and 2 to 10 for double jeopardy. The kids may either eat their earnings or save them to bet on Final Jeopardy. Two big bags of candies should be enough--you will need about 400 pieces to play the entire game.

    Jeopardy rules:
    • Format:
      1. Coach tapes the appropriate game board (jeopardy or double jeopardy) to the board and puts a postit note on answered questions as the game progresses.
      2. Coach picks the categories and the levels (1 to 5 candies for Jeopardy, 2 to 10 candies for Double Jeopardy) and gives the problems verbally.
      3. Kids must answer with "What is ...?"
      4. Coach starts with the simpler problems (1 candy) and progresses to the more difficult problems (5 to 10 candies).
      5. Kids raise their hands to answer a question. First hand up gets to answer.
      6. Paper and pencil are OK. Calculators are OK, although they will be a big disadvantage, as they will slow the kids down.
      7. Coach explains the following rules before the game begins.
    • Correct answer: Correct answers get the number of candies associated with the question. A kid who gives a correct answer cannot answer the next question (gotta spread the candy around!).
    • Incorrect answer: Kids must give back the number of candies associated with an incorrect answer. Kids cannot go negative. Lowest number of candies any kid has is zero. If a kid gives an incorrect answer, any kid can raise their hand to answer the question with the same consequences.
    • Teams: If you have too many kids (more than about 6) form them into teams
    • Final Jeopardy Kids write down their wagers on pieces of paper and give them to the coach before the coach gives the question. Kids must have the number of candies in their wagers (if the kid has 9 candies they cannot wager 10).
    • Celebration: Small celebration for the winner(s)! Encourage winners to share their 'winnings' with the other kids.