TEC Lesson Plan
The Broken Calculator

Contributor Information
Name: James P. Dildine modified by Melissa Protomastro
Date: 7/12/99
email address: melissa_protomastro@placesmail.pinellas.k12.fl.us
School: J.L. Carwise Middle

Standards

Sunshine State Standards
Strand: Number Sense, Systems and Operations
Standard and Benchmarks:
The student understands the effects of operations on numbers and the relationships among these operations, selects appropriate operations, and computes for problem solving.
MA.A.3.3.1 Understands and explains the effects of addition, subtraction, multiplication and division on whole numbers, fractions (including mixed numbers), and decimals, including the inverse relationships of positive and negative numbers.
MA.A.3.3.2 Selects the appropriate operation to solve problems involving addition, subtraction, multiplication, and division of rational numbers, ratios, proportions, and percents, including the appropriate application of the algebraic order of operations.

NET Standards
Technology productivity tools
T.3.3.4 Use content-specific tools, software, and simulations (e.g., environmental probes, graphing calculators, exploratory environments, Web tools) to support learning and research. 6-8

Lesson Plan

Title: The Broken Calculator

Technology Resource Requirements: calculators

Subject Area(s): mathematics

Grade Level: middle

Short Description:

The student will demonstrate the effects of operations on numbers and the relationships among these operations by exploring what series of calculator keys could be pushed to solve a problem if a particular key is not working. How students arrive at the answer in selecting the appropriate application of the algebraic order of operations is the focus.

Approximate Time Required:

one class period (could be an on-going project by having students post challenges and solutions on a bulletin board)

Procedure:

This lesson is adapted from James P. Dildine’s “The Island of Discarded Calculators”. Use his scenario to grab attention or simply challenge the students to “solve 18 times 25 (pause) now your 5 key is broken, solve the same problem without that key.

Students may work individually or in small groups. Distribute problems to each group with each problem being assigned to at least two groups. Sample problems

Assessments:

Students will present their solutions. This is a good problem solving activity and an excellent way to informally evaluate a students grasp of the effect of operations.