Reading Your Electric Meter

Transcription

1 AK Reading Your Electric Meter Target grades: 3-5 AK ELAM Standards: Mathematics 3.MD.4. 4.NBT.4. AK Science GLEs [3/4/5] SA1.1 [3/4/5] SA1.1 [3/4/5] SA1.2 [3/4] SA2.1 NGSS See page 6. Set up time: 15 minutes Class time: Approximately two class sessions: one session for learning how to read the meter and one for writing a science report and sharing students findings. The lesson also requires homework for one week of collecting daily data. Overview: Students will learn how to read their home electrical meter, record the amount of energy their household uses each day for a week, and write a science report. Objectives: This lesson will teach students how to read their electric meter and record home energy usage. Using the scientific method, students will hypothesize how much their home electricity consumption fluctuates (i.e., higher energy use on certain days), observe and collect data over the course of a week, and then write a science report with a graph to present their results. Materials: Pencils Reading Your Electric Meter student worksheet Background: Knowing how to read and interpret the electric meter at your home can greatly increase awareness of your household s energy use and how this energy use is higher on certain days (e.g., laundry day, weekends when household members are home all day, very cold days, etc.) and lower on other days (e.g., weekdays when kids are at school/ parents at work, warmer days, etc.). An electric meter records energy usage so that the utility company can determine a household s electric bill. Energy = Power x Time: Electric meters measure energy in kilowatthours (kwh). This is the amount of power (number of kilowatts) used over a certain length of time (one hour): 1 kw X 1 hour (h)=1 kwh Energy use by household appliances is usually rated in watts (W): 1,000 W = 1 kw A 60 W appliance that is used for 1 hour would use 0.06 kwh. In order to calculate this, we must convert watts to kilowatts: 60W X 1kW/1000W X 1 h=0.06 kwh

2 2 In Alaska, the price for a kilowatt-hour varies greatly depending on location and fuel used for power generation, such as natural gas, hydropower, coal, or diesel. The average cost of electricity in the nation is about $0.12 / kwh, though energy costs tend to be higher than elsewhere in the nation, especially in rural Alaska. In 2000, the price of electricity was $0.216 / kwh in Unalaska, $0.396 / kwh in Elim, and $0.464 / kwh in Cold Bay, and upwards of $0.75 / kwh in some communities where fuel must be flown in. Vocabulary List: electric meter - a device that measures the amount of electricity used. Electric meters are used by electric companies to measure electricity use by their customers for homes or businesses, and portable electric meters such as the Kill-A-Watt meter can measure the electricity used by individual appliances. energy - the ability of a system to do work; this might refer to either potential or kinetic energy. Potential energy (stored energy) includes chemical, mechanical, nuclear, and gravitational energy. Kinetic energy (motion energy) includes radiant, thermal, motion, sound, and electrical energy. kilowatt (kw) - a unit used to measure power. One kilowatt equals 1,000 watts (W). kilowatt-hour (kwh) - a unit used to measure energy. A kilowatt-hour is the amount of energy used if you use 1000 watts for one hour and is equivalent to 3.6 million joules and 3,412 BTUs. power - the rate at which work is performed or energy is converted; units of power include both an amount of energy and a length of time. scientific method (scientific process) - the methodological steps involved to pursue knowledge which includes asking a question, conducting background research, creating a hypothesis, collecting data through observations and/or an experiment, analyzing the data, drawing a conclusion, and communicating the results. watt (W) - a unit used to measure power. One watt equals one joule per second (j/s). A typical incandescent light bulb uses 60 W to keep the light bulb lit for one hour. Gear Up: Lead a class discussion about home energy use; ask them what energy they use during the day and if there are certain days their family might use more energy. Record students responses on the board. Reading an electric meter: Next, tell students that most homes have an electric meter outside so the utility company can track that home s energy usage. While meters at newer homes are likely to give a numeric or digital reading output, older meters display with dials. This meter contains 4 dials which, from left to right, represent the thousands, hundreds, tens, and ones:

3 3 Image Credit: The dials on the electric meter would read 3,256 kwh. Notice that some of the dials turn clockwise while some turn counter-clockwise. If the dial is in between two numbers, always read the smaller number. To determine the amount of energy used over a certain amount of time, subtract the original reading from the most recent reading (and the units are in kwh). If your classroom setup permits, have your class take the Energy Quiz Show from This online quiz is a great way to get them thinking about different forms of energy and where they come from. Another Gear Up is to take pictures of different meters and at different times, or to simply draw different meters on the board to have the students practice reading meters. Activity: Explain to students they will use the scientific method to track their home s energy usage for a week and write a scientific report on their findings. They will pick a time when they are home every day to read the electric meter at approximately 24-hour intervals to keep their observations consistent. Hand out the Electric Meter Experiment worksheets and have them begin to fill out the problem, hypothesis, materials, and procedure sections in class. They will then collect the electric meter data over the course of the week and fill in the remaining sections on the worksheet. Extension: 1. Have groups of three or four students graph their results on the same graph to illustrate 1) how data compared from household to household and 2) to illustrate how multiple data sets can be compared on the same graph. 2. Invite a representative from the local utility to come speak to the class about electrical use in the community or organize a field trip to a local power plant.

4 4 Additional Resources: Alaska Electric Light and Power Company This website provides an online guide to reading an electric meter. Public Broadcasting Service This website provides information, lessons, and games on household energy consumption and a tutorial on how to read your electric meter. Energy Star The Energy Star website has fun facts and lessons on everything related to energy: what it is, where it comes from, types of energy, and how it can be conserved. Alaska Mathematics Standards: Represent and interpret data. 3.MD.4. Draw a scaled picture graph and a scaled bar graph to represent a data set with several categories. Solve one- and two-step how many more and how many less problems using information presented in scaled bar graphs. For example, draw a bar graph in which each square in the bar graph might represent 5 pets. Use place value understanding and properties of operations to perform multi-digit arithmetic. 4.NBT.4. Fluently add and subtract multi-digit whole numbers using any algorithm. Verify the reasonableness of the results. Alaska Science Grade Level Expectations: The student demonstrates an understanding of the processes of science by: [3] SA1.1 asking questions, predicting, observing, describing, measuring, classifying, making generalizations, inferring, and communicating. [3] SA1.2 observing and describing the student s own world to answer

5 5 simple questions. [4] SA1.1 asking questions, predicting, observing, describing, measuring, classifying, making generalizations, inferring, and communicating. [4] SA1.2 observing, measuring, and collecting data from explorations and using this information to classify, predict, and communicate. [5] SA1.1 asking questions, predicting, observing, describing, measuring, classifying, making generalizations, inferring, and communicating. [5] SA1.2 using quantitative and qualitative observations to create inferences and predictions. The student demonstrates an understanding of the attitudes and approaches to scientific inquiry by: [3] SA2.1 answering how do you know? questions with reasonable answers. [4] SA2.1 supporting the student s own ideas with observations and peer review.

6 Alaska Energy Map 6 Next Generation Science Standards Standard: PS3C - Relationship Between Energy and Forces Performance Expectation: 4-PS3-2 - Make observations to provide evidence that energy can be transferred from place to place by sound, light, heat, and electric currents. (This lesson is one step toward reaching the performance expectation above.) Dimension Name or NGSS code/citation Matching student task or question taken from the lesson Science and Engineering Practice Disciplinary Core Idea Crosscutting Concept Constructing Explanations and Designing Solutions Use evidence (e.g., measurements, observations, patterns) to construct an explanation. (4-PS3-1) PS3.A: Definitions of Energy Energy can be moved from place to place by moving objects or through sound, light, or electrical currents. (4-PS3-2), (4- PS3-3) Science is a Human Endeavor: Science affects everyday life. (4-PS3-2) Step 5: Results and Observations from Student Worksheet for Reading Your Electric Meter. Students take daily readings for their electric meter. They should note any special occurrences that might impact usage on particular day. (e.g., laundry day, very cold day) Step 5: Results and Observations from Student Worksheet for Reading Your Electric Meter. Students take daily readings for their electric meter. Discussion of the graphs and data collected by students of the electrical energy usage for a week at home. Revised March, 2015 Acknowledgment: This material is based upon work supported by the Department of Energy under Award Number DE-EE Disclaimer: This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.