Math 35
Calling All Students
Mrs. Forest wanted to plan how to contact her students by phone in case the field trip they were going on the next day needed to be canceled. She decided to call one student who would then call 2 other students. Each of these students would then call 2 other students. This would continue until all students had been called. Mrs. Forest has 31 students. How many students will need to make phone calls if Mrs. Forest calls the first student?
Suggested Grade Span
Grades 35
Grade(s) in Which Task Was Piloted
Grade 4
Alternative Versions of Task
More Accessible Version:
Mrs. Forest wanted to plan how to contact her students by phone in case the field trip they were going on the next day needed to be canceled. She decided to call one student who would then call 2 other students. Each of these students would then call 2 other students. This would continue until all students had been called. Mrs. Forest has 15 students. How many students will need to make phone calls if Mrs. Forest calls the first student?
More Challenging Version:
Mrs. Forest wanted to plan how to contact her students by phone in case the field trip they were going on the next day needed to be canceled. She decided to call one student who would then call 2 other students. Each of these students would then call 2 other students. This would continue until all students had been called. Mrs. Forest has 31 students. How many students will need to make phone calls if Mrs. Forest calls the first student? Find a rule for determining how many phone calls will be made for any number of students.
NCTM Content Standards and Evidence
Algebra Standard for Grades 35
Instructional programs from Pre Kindergarten through grade 12 should enable students to...
 Understand patterns, relations and functions.
 NCTM Evidence: Describe, extend, and make generalizations about geometric and numeric patterns.
 Exemplars Task Specific Evidence: Most students will create a tree diagram to solve this task to identify and extend the growing pattern.
Time/Context/Qualifiers/Tip(s) From Piloting Teacher
This is a short to medium length task.
Links
This task could link to a class field trip, to a unit on weather (the cause of the canceled field trip), or to a unit on the history of the telephone.
Common Strategies Used to Solve This Task
Most students will use a tree diagram to solve this task.
Possible Solutions
Original Version:
15 Callers
More Accessible Version:
7 Callers
More Challenging Version:
If an odd number of students: (N  1) / 2 , where N = number of students that need to be called. If an even number of students: N / 2, where N = number of students that need to be called.
Task Specific Assessment Notes
General Notes: Most students will create a tree diagram to solve this task. This task does not lend itself to eliciting a lot of mathematical language.
Task Specific Rubric/Benchmark Descriptors
Click on a level for student example. 


Novice  The Novice will not have an approach that will work. 
Apprentice  The Apprentice will attempt a tree diagram, but it will be incorrect or incomplete. 
Practitioner  The Practitioner will have a correct and systematic approach to solving the task. The Practitioner will have a correct solution and may make observations about patterns in the solution. 
Expert  The Expert will analyze the situation in mathematical terms, achieving a correct solution that is well communicated. 
Novice
Calling All Students
Mrs. Forest wanted to plan how to contact her students by phone in case the field trip they were going on the next day needed to be canceled. She decided to call one student who would then call 2 other students. Each of these students would then call 2 other students. This would continue until all students had been called. Mrs. Forest has 31 students. How many students will need to make phone calls if Mrs. Forest calls the first student?
Apprentice
Calling All Students
Mrs. Forest wanted to plan how to contact her students by phone in case the field trip they were going on the next day needed to be canceled. She decided to call one student who would then call 2 other students. Each of these students would then call 2 other students. This would continue until all students had been called. Mrs. Forest has 31 students. How many students will need to make phone calls if Mrs. Forest calls the first student?
Practitioner
Calling All Students
Mrs. Forest wanted to plan how to contact her students by phone in case the field trip they were going on the next day needed to be canceled. She decided to call one student who would then call 2 other students. Each of these students would then call 2 other students. This would continue until all students had been called. Mrs. Forest has 31 students. How many students will need to make phone calls if Mrs. Forest calls the first student?
Expert
Calling All Students
Mrs. Forest wanted to plan how to contact her students by phone in case the field trip they were going on the next day needed to be canceled. She decided to call one student who would then call 2 other students. Each of these students would then call 2 other students. This would continue until all students had been called. Mrs. Forest has 31 students. How many students will need to make phone calls if Mrs. Forest calls the first student?