Grade 6 Problem Solving Program 4-29-14

Name______Date______

Cell Phone Plans (Assessment)

Gertrude is deciding which cell phone plan is the best deal for her to buy. Super Cell charges a monthly fee of and also charges per call. She makes a note that the equation is , where is the monthly charge and is the number of calls placed. Global Cellular has a plan with no monthly fee, but charges per call. She makes a note that the equation is , where is the monthly charge and is the number of calls placed. Both companies offer unlimited text messages.

a. Make a table for both companies showing the cost of service, , for making from to calls per month. Use multiples of .

Number of Super Cell Global Cellular Calls,

b. Construct a graph for the two equations on the same graph. Use the number of calls, , as the independent variable, and the monthly charge, , as the dependent variable.

Grade 6 Problem Solving Program 4-29-14

c. Which cell phone plan is the best deal for Gertrude? Defend your answer with specific examples. Grade 6 Problem Solving Program 4-29-14

Cell Phone Plans Rubric

Cell Novice - Missing or Apprentice - Missing or Practitioner – A correct Expert - A correct answer Phone incorrect answer and little incorrect answer but evidence answer with some evidence supported by substantial evidence of reasoning or of some reasoning or of reasoning or application evidence of solid reasoning Plans application of mathematics application of mathematics to of mathematics to solve the or application of to solve the problem. solve the problem. problem, or an incorrect mathematics to solve the answer with substantial problem. evidence of solid reasoning or application of mathematics to solve the problem.

a Student is not able to make A table is drawn showing the A table is drawn showing the Both tables are calculated a table with multiples of 20 number of calls and number of calls and accurately. Columns (or rows) calls or cannot calculate company/equation, but company/equation. One are labeled clearly, including 6.EE.9 monthly charge based on neither column is accurately column is accurately the equation. number of calls. calculated. calculated, but the other has errors. b Student is not able to draw a An attempt is made to graph A graph is drawn with minor The graph is drawn without graph from the data in the the points from the table. mistakes or omissions. It error (i.e., graph is titled, axes table. Several mistakes or omissions includes at least three of the labeled, units included on 6.EE.9 are present. four criteria of a perfect axes, and points plotted graph. accurately). c Student cannot conclude Student chooses one plan or Student concludes that the Student concludes that the which plan is better or the other, showing support for best deal depends on the best deal depends on the 6.EE.9 chooses a plan without that plan. Student does not number of calls placed in a number of calls placed in a evidentiary support. recognize that the best deal month. Complete analysis is month. The break-even point, depends on the number of not described. calls costing , is calls placed. identified. Answer specifically states that Super Cell is the better deal if the number of calls per month is , and Global Cellular is a better deal if the number of calls per month is . Grade 6 Problem Solving Program 4-29-14

Name_____Sample Answer______Date______

Cell Phone Plans (Assessment)

Gertrude is deciding which cell phone plan is the best deal for her to buy. Super Cell charges a monthly fee of and also charges per call. She makes a note that the equation is , where is the monthly charge and is the number of calls placed. Global Cellular has a plan with no monthly fee, but charges per call. She makes a note that the equation is , where is the monthly charge and is the number of calls placed. Both companies offer unlimited text messages.

d. Make a table for both companies showing the cost of service, , for making from to calls per month. Use multiples of .

e. Construct a graph for the two equations on the same graph. Use the number of calls, , as the independent variable, and the monthly charge, , as the dependent variable. Grade 6 Problem Solving Program 4-29-14

f. Which cell phone plan is the best deal for Gertrude? Defend your answer with specific examples.