# Ohm's Law made easy with a spreadsheet

In this lesson, students will use math word problems to help them input information into a spreadsheet that will use Ohm's law to calculate current and resistance using common household appliance wattages.

**A lesson plan for grades 6–9 Computer/Technology Skills, Mathematics, and Science**

## Learning outcomes

Students will:

- solve word problems to find information needed to use a given spreadsheet
- use spreadsheet to solve problems based on Ohm’s Law
- manipulate spreadsheet to answer “what if” questions

## Teacher planning

### Time required for lesson

1 hour

### Materials/resources

### Technology resources

- Ohm’s law spreadsheet saved on disks for students
- computer lab setting works best
- calculators or access to one via computer
- Microsoft Excel or Works is needed to view the spreadsheet

## Pre-activities

- Students will have already had a lesson on Ohm’s Law and how it helps to identify how power, current, and resistance are related.
- Students will have already completed Ohm’s Law problems without the use of a spreadsheet to explore how changing current and resistance can affect power and vice versa.
- Students will already have had experience inputting data to a spreadsheet.
- Students will have had experiences with solving for an unknown in word problems.

## Activities

- Teacher gives students a copy of the Ohm’s Law questions.
- Teacher and students work through a problem to review how to solve for an unknown in a word problem.
- Students open Ohm’s Law spreadsheet on the computer.
- Students input data to spreadsheet.
- Students print out a copy of spreadsheet with their name on a row at the bottom of the spreadsheet.
- Students manipulate data to answer “what if” type questions about the spreadsheet.

## Assessment

Printout of spreadsheet after student has input necessary data will be used to assess students’ answers to word problems.

Student answers to Ohm’s Law questions will be used to assess students’ knowledge of how the formula for Ohm’s Law can be manipulated and their ability to manipulate data within a spreadsheet to answer “what if” questions.

## Supplemental information

Attachments:

### Comments

I have extended this lesson to have students create their own spreadsheet that calculates horsepower. Then students run the gym steps for time, measure the height of the gym steps, and weigh each other. They input this data in their spreadsheet to calculate the amount of power they generated running the steps and then we discuss what types of appliances they could run off that power if they could continue to generate that amount of power for an extended amount of time. Most students decide they would rather pay for electricity from the power plant!

- North Carolina Essential Standards
- Science (2010)
#### Grade 7

- 7.P.2 Understand forms of energy, energy transfer and transformation and conservation in mechanical systems. 7.P.2.1 Explain how kinetic and potential energy contribute to the mechanical energy of an object. 7.P.2.2 Explain how energy can be transformed from...

#### Physical Science

- PSc.3.3 Understand electricity and magnetism and their relationship. PSc.3.3.1 Summarize static and current electricity. PSc.3.3.2 Explain simple series and parallel DC circuits in terms of Ohm’s Law. PSc.3.3.3 Explain how current is affected by changes...

## North Carolina curriculum alignment

### Computer Technology Skills (2005)

#### Grade 7

**Goal 2**: The learner will demonstrate knowledge and skills in the use of computer and other technologies.**Objective 2.02**: Enter/edit data and use spreadsheet features and functions to project outcomes and test simple "what if..." statements in content assignments. Strand - Spreadsheet

### Mathematics (2004)

#### Grade 7

**Goal 5**: Algebra - The learner will demonstrate an understanding of linear relations and fundamental algebraic concepts.**Objective 5.04**: Develop fluency in the use of formulas to solve problems.

### Science (2005)

#### Grade 7

**Goal 1**: The learner will design and conduct investigations to demonstrate an understanding of scientific inquiry.**Objective 1.09**: Use technologies and information systems to:- Research.
- Gather and analyze data.
- Visualize data.
- Disseminate findings to others.

**Goal 2**: The learner will demonstrate an understanding of technological design.**Objective 2.02**: Use information systems to:- Identify scientific needs, human needs, or problems that are subject to technological solution.
- Locate resources to obtain and test ideas.

**Goal 6**: The learner will conduct investigations, use models, simulations, and appropriate technologies and information systems to build an understanding of motion and forces.**Objective 6.03**: Evaluate motion in terms of Newton's Laws:- The force of friction retards motion.
- For every action there is an equal and opposite reaction.
- The greater the force, the greater the change in motion.
- An object's motion is the result of the combined effect of all forces acting on the object:
- A moving object that is not subjected to a force will continue to move at a constant speed in a straight line
- An object at rest will remain at rest.