Lesson Plan # 17 - Introduction to
Probability
Note to coach: Copy the "cards and dice images" handout onto the back of the probability handout.
- (5 min) Mental Math
- Multiply 1/3 by 3/8 and reduce [1/8]
- Start with 125, multiply by 10, then subtract 50 [1200]
- What is the perimeter of a rectangle whose sides are 10 feet and 5
feet? [30 feet]
- What is the area of a triangle whose base is 8 feet and whose
height is 6 feet? [24 sq. ft.]
- What is the decimal for 526 divided by 100? [5.26]
- (5 min) Review of homework #15 (<= 3 problems)
- (10 min) Introduce probability:
- Pass out the Probability handout
- Explain that probability has to do with the future. Contrast
it to statistics:
Past |   | Future |
Statistics about things that have already occurred |
NOW! |
Probability of things happening in the future |
- Define probability as a fraction:
NUMBER OF THINGS YOU ARE LOOKING FOR
-------------------------------------
TOTAL NUMBER OF THINGS
- Discuss maximum probability (1), minimum probability (0) and what they
mean. Ask students for examples.
- Use examples in the handout to illustrate basic probabilities.
Use these additional examples, if you wish, and ask students to
solve them:
- Probability of pulling the 6 of hearts out of a deck of 52 cards.
[1/52]
- Probability of drawing a blue marble out of the bag in the handout
[5/7]
- Probability of drawing a blue or a red marble out of the bag in the
handout [7/7 or 1]
Note: this discussion goes much
better
if you bring things to illustrate probability
with you, like dice, cards,coins, or
marbles.
One technique that I have used successfully
is to spread an entire deck of cards out on
the floor in a rectangle, with each suit
being a row. When you then ask students
for probabilities of drawing certain cards
or suits, they can see it pictorially for themselves.
Here are big cards that work well: big cards.
If you cannot do this, use the Cards and dice page to illustrate the probabilities.
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- (Remainder of class) In-class Exercise.
- Hand out homework as students successfully complete the in-class
exercise.
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