So, When Will I Ever See a Negative Number?

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Objective

SWBAT show how negative numbers are used in a real world context.

Big Idea

Okay so... Negative numbers aren't just make believe? Seeing negative numbers in real world context.

Curriculum Reinforcer

10 minutes

Students will complete 3 problems to review units 1 through 6. The curriculum reinforcer, is a daily practice piece that is incorporated into almost every lesson to help my students to retain skills and conceptual understanding from earlier lessons. My strategy is to use Spiraled Review to help my students retain what they learned during the earlier part of the year. This will help me to keep mathematical concepts fresh in the students mind so that the knowledge of these concepts become a part of students' long term memories.

Engagement

10 minutes

To open up today’s lesson, we will have a discussion based upon the following question; Where do we see integers in real life?

 

The types of answers that I should receive are as follows:

  • Debits & credits (bank account)
  • Golf
  • Temperature
  • Above & below sea level

Instruction & Teacher Modeling

10 minutes

In today’s instruction, I will first review the position of positive and negative integers and rational numbers on the vertical number line. Then, using the opening discussion, I will discuss with my students what the position tells us. This discussion will be within the real world contexts of elevation, debits/credits, and temperature.

 

To ensure that my instruction stays within the confines of the real world context, I will display a thermometer on my digital projector (if you do not have one in your classroom, you can draw a thermometer on your board). With this depiction of a thermometer, I will present students with different scenarios involving temperature including the following:

  • Marking temperature on the thermometer
  • Understanding the freezing point and below freezing.
  • Celsius versus Fahrenheit.
  • The distance between one temperature and another (i.e. a cities record high versus its record low)

 

Next, I will write a scenario involving a bank account and display it on the digital projector. The scenario will be something like the following:

  • Jackie has $250 in her bank account. She decides to go shopping and spends $125.00 on clothes. She then goes to the grocery store and spends $100 dollars on groceries. She uses $20.00 to put gas in her car. Later, Jackie realizes that she didn’t wait for one of her bills to clear her account. That bill was $80.00. How much money does Jackie have in her account after everything comes out of her account?

Using this scenario, I will show students the meaning of an overdrawn account, being in the negative, and owing the bank. I will also discuss with them how -$200.00 is less than -$10.00.

 

After the demonstration concerning banking, I will display a picture on the digital projector that will depict above sea level, sea level, and below sea level. I will also place a hot air balloon in the picture and tell the students that the hot air balloon is 1500 feet in the air. After telling my student this information, I will then ask them, from where do they think I am measuring the height of the balloon? Using this scenario I will illustrate the meaning of above and below sea level. 

Try It Out

5 minutes

For guided practice, the students will be given their own copy of the scenarios presented during the instruction. The students are to take notes and label their copies so that they will have this information to study at a later date.

 

The students will also be given the following two questions to ensure that they understood the concept taught today during instructions.

1. Which situation would you represent with a negative integer?

A) A mountain climber descending a mountain

B) A price increase

C) A person winning a sum of money

D) An elevator going from the 2nd floor to the 5th floor

2. New Orleans has an elevation of 7 feet below sea level. How is that elevation, in feet,           represented as an integer?

3. Which situation can be represented by the integer 10

A) A temperature drop of 10 degrees Fahrenheit.

B) 10 seconds before takeoff

C) A growth of 10 centimeters

D) A fall of 10 feet.

Independent Exploration

20 minutes

For today’s independent practice, my students will complete a mini-project. They will all have to pick a number from a container. The container will be filled with number 1’s, 2’s. and 3’s. The number that each student randomly chooses, will determine which mini-project the students will have to complete. The projects are as follows:

  1. Elevation (Above & Below Sea Level): The students will be given a set of marine animals and a set of different birds. They will have to create a poster to depict their elevation.
  2. Temperature: Students will have to look up the record high and lows for each month of the year in the city of Denver, CO and create a poster that shows those temperatures on a thermometer.
  3. Keeping Track: The students who pick this project will be given the balances of three different accounts of three different people. The students will also be given a set of debits that are to be taken away from each of those accounts. The students who choose this project will calculate each person’s final balance.

***For each project, the students will need to list their items from least to greatest and write a brief essay about what they have learned.

Closing Summary

15 minutes

Student Presentation: Select students will be chosen to present their final product from the independent practice.