Using Variables
The Lesson Activities will help you meet these educational goals:
· Content Knowledge—You will write, read, and evaluate expressions in which letters stand for numbers.
· Mathematical Practices—You will make sense of problems and solve them.
· Inquiry—You will perform an investigation in which you will communicate your results in written form.
· STEM—You will grow in your understanding of mathematics as a creative human activity.
· 21st Century Skills—You will use critical-thinking and problem-solving skills.
Directions
You will evaluate some of these activities yourself, and your teacher may evaluate others. Please save this document before beginning the lesson and keep the document open for reference during the lesson. Type your answers directly in this document for all activities.
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Self-Checked Activities
Read the instructions for the following activities and type in your responses. At the end of the lesson, click the link to open the Student Answer Sheet. Use the answers or sample responses to evaluate your own work.
Algebraic Expressions
Recall that Betty arranged equal numbers of movies on four shelves of a shelving unit and placed 6 of her favorite movies on the top shelf. If x is the number of movies on each shelf, the expression for the total number of movies on the shelving unit is 4x + 6.
a. If each of the 4 shelves holds 12 movies, how many movies does Betty have on her shelving unit? Show your work.
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b. If each of the 4 shelves holds 14 movies, how many movies does Betty have on her shelving unit? Show your work.
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c. Betty rearranged the movies on her shelving unit after a few days. She placed equal numbers of movies on the bottom 3 shelves, and 10 movies on each of the top two shelves. If x is the number of movies on each of the bottom 3 shelves, the expression for the total number of movies on the shelving unit is 3x + 20. How many movies are on the shelving unit if there are 11 movies on each of the bottom 3 shelves?
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d. Write an expression for the quotient of b divided by the difference of two minus three.
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e. Evaluate the expression you got in part d for b = 8.
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f. Write an expression for two times the difference of eight and d.
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g. Evaluate the expression you got in part f for d = 5.
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h. Write an expression for the quotient of twelve divided by the sum of two times g and one.
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i. Evaluate the expression you got in part h for g = 1.
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How did you do? Check a box below.
Nailed It!—I included all of the same ideas as the model response on the Student Answer Sheet.
Halfway There—I included most of the ideas in the model response on the Student Answer Sheet.
Not Great—I did not include any of the ideas in the model response on the Student Answer Sheet.
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