Lesson 2
Name: Lauren Thibodeaux
Title of lesson: Probability of Catching Disease
Date of lesson: April 27, 2004
Length of lesson: 45 minutes
Description of the class:
Name: Algebra
Grade level: 9th
Honors or regular: Either
TEKS addressed:
(a) Basic understandings.
(1) Foundation concepts for high
school mathematics. As presented in Grades K-8, the basic understandings of
number, operation, and quantitative reasoning; patterns, relationships, and
algebraic thinking; geometry; measurement; and probability and statistics are essential foundations for all work in
high school mathematics. Students will continue to build on this foundation as
they expand their understanding through other mathematical experiences.
(a) Basic understandings.
(1) Foundation concepts for high
school mathematics. As presented in Grades K-8, the basic understandings of
number, operation, and quantitative reasoning; patterns, relationships, and
algebraic thinking; geometry; measurement; and probability and statistics are essential foundations for all work in
high school mathematics. Students continue to build on this foundation as they
expand their understanding through other mathematical experiences.
The Lesson:
Students will be able to:
á Find probabilities
á Write probabilities as a fraction or as a ratio
á Understand how probabilities change as objects are removed from the total
á Discuss how probabilities remain unchanged when objects are put in a different order or mixed around
III. Resources, materials and
supplies needed
Index cards, paper, pens
IV. Supplementary materials, handouts.
Teacher Does Student Does
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Engage: Learning Experience As students walk into class they will notice an assignment written on the board: ÒAll boys sit on one the left side of the room and all girls sit on the right side of the room. All left-handed students sit in the front row and all right-handed students sit in any row except the front.Ó When the bell rings the teacher will ask all students to stand and count-off using very loud voices. The teacher will then write the total number of students on the board. The teacher will then ask all girls to sit and all boys to count-off using very loud voices. The teacher will then write the number of boys on the board next to the total number of students in two ways: as a ratio and as a fraction. The teacher will then call on one student to say the ratio aloud and another student to say the fraction aloud. The teacher will then do the same with the girls in the class. The teacher will explain that the total number of students in the class represents a whole and the number of girls in the class represents a part of the whole. The teacher will explain that if one student were randomly chosen from the class, the probability of that student being a boy is the part over the whole written on the board. The teacher will then ask all left-handed students to raise their hands and the teacher will write this number over the total number of students. The teacher will do the same for right-handed students and will then ask the students what the probability of a randomly selected student being left-handed. Questions 1. What is the probability of a randomly selected student being right-handed? Left-handed? A boy? A girl? |
What the students are doing
Students will sit in the area that represents them. Students will stand and count-off in very loud voices. Girls will sit and boys will stand and count-off in very loud voices. Students will say the ratio or fraction as directed.
Expected Student Answers 1. Answer written on board |
Evaluate
If three girls and three boys were sent to the counselorÕs office for the class period, what is the new probability of a randomly chosen student in the class being a boy?
Teacher Does Student Does
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Explore: Learning Experience(s) The teacher will explain that it is possible to predict the probability of getting a disease. The teacher will explain that during flu season, 1 out of every 3 people will get influenza. The teacher will tell the students that there is an index card taped under each desk. Some of the index cards have a red spot, which means that the student got the flu, while other cards have a blue spot, which means that the student did not get the flu. In addition, each card has a number which is the group they will be in. There will be 3 members per group. The teacher will ask the students to take the index card from under their desks and get with their group members. The teacher will then ask each group how many of the group members are infected with the flu. As the students give their answers the teacher will write them on the overhead. After all groups have spoken, the teacher will point out that some groups have no infected members while others have two or even three infected members.
Questions
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What the students are doing
Expected
Student Answers
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Evaluate
If three non-infected students left the room to go the bathroom, what is probability of catching the flu?
Teacher Does Student Does
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Explain: Learning Experience(s) The teacher will ask all students to line up in a straight line. The teacher will then ask every third person to step out of line. The teacher will ask if all students that stepped out of line are infected with the disease. When the students say no, the teacher will ask how this is possible. The teacher will explain that the students did not line up in exactly the correct order for every third person to have the disease. The teacher will ask the students to step back into a straight line. The teacher will ask if the probability of getting influenza has changed from 1 out of 3. The teacher will ask if every third person has to get the disease for the statistic 1 out of 3 to be correct. Questions 1. How many students are infected with the disease? 2. If we rearrange our order, how many students are infected with the disease? 3. Does the order in which you line up change the number of people infected with the disease? Why or why not? |
What the students are doing Lining up in a straight line. Every third person will step out o line.
Answer questions. Expected
Student Answers
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Evaluate
The teacher will tell the students that 1 in every 100 people will get a particular disease in Zimbabwe. If the population is 1 million, how many people will get the disease?
Teacher Does Student Does
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Extend / Elaborate: Learning Experience(s) The teacher will walk around with a jar of marbles. The teacher will tell the students that there are a total of 50 marbles in the jar and 5 of them contain a disease. If the marble is clear then it does not have a disease, but if it is red then it does have a disease. The teacher will ask the class, ÒWhat is the probability of choosing a red marble? The teacher will ask one student to choose a marble and take it out of the jar. Then the teacher will ask the class, ÒNow, what is the probability of choosing a red marble?Ó The teacher will continue with this line of questioning until the students understand the concept thoroughly or until the period ends. Questions 1. What is the probability of choosing a red marble? 2. Now, what is the probability of choosing a clear marble? |
What the students are doing Listening. Answering questions. Choosing a marble. Answering questions. Expected
Student Answers
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Evaluate
Students will be told that 4 out of every 5 chickens lay at least one egg on Monday. There are 20 chickens in the coop. If one chicken is randomly chosen from the coop, what is the probability that it lays no eggs on Monday?