1. Extension Activities:
Energy and Engineering Trends:
Systems of Equations
Duration: 90 min
Standards: HSA.CED.A.1
HSA.CED.A.2
HSA.CED.F-IF.4
HSA.CED.A-REI.6
HSA.CED.A-REI.11
Overview: Students must determine ‘which is the better lightbulb?”. In the previous lesson they determined energy efficiency/cost efficiency. In this lesson, the purchase prices of the lightbulbs are introduced and students must answer the same question as well as a follow up question, using systems of equations to solve.
Algebra 1
Materials:
Worksheet
Graphing calculator (TI-84)
Pencils/Pens
Graphing Paper
Extension Activities:
Have students research different energy efficient appliances.
Vary energy usage depending on weekday/weekend to challenge higher-level learners.

2. Procedure: Teacher Tips:
Students will be introduced to the purchase price of each lightbulb and asked again, “Which lightbulb should I buy?” After a class discussion, they will then be asked “How long will it take for me to start having cost-benefits from my purchase?
Students will be instructed on systems of equations and the concept of break-even point.
Students will solve the initial class question by graphing and solving systems of equations for each lightbulb pair.
Teacher Tips:
Have higher order thinking questions prepared ahead of time to guide discussion.