Lab Name Signal Strength and Proportionality
Subject Area Mathematics
Grade 7
Topic Ratios, Rate of Change, and Unit Rate.
Experiment Title Signal Strength and Proportionality.
Hardware Walkie-Talkie, COSMOS Node, and Chronograf.
Software COSMOS toolkit framework, and GNU Radio.
Number of Sessions to teach the topic 1 - 2 sessions
Educational standards to be addressed
  • CCSS.Math.Content.6.EE.C.9
    Use variables to represent two quantities in a real-world problem that change in relationship to one another; write an equation to express one quantity, thought of as the dependent variable, in terms of the other quantity, thought of as the independent variable. Analyze the relationship between the dependent and independent variables using graphs and tables, and relate these to the equation. For example, in a problem involving motion at constant speed, list and graph ordered pairs of distances and times, and write the equation d = 65t to represent the relationship between distance and time.
  • CCSS.Math.Content.6.RP.A.1
    Understand the concept of a ratio and use ratio language to describe a ratio relationship between two quantities.
  • CCSS.Math.Content.6.RP.A.3.b
    Solve unit rate problems including those involving unit pricing and constant speed.
  • CCSS.Math.Content.7.EE.B.4
    Use variables to represent quantities in a real-world or mathematical problem, and construct simple equations and inequalities to solve problems by reasoning about the quantities.
  • CCSS.Math.Content.7.RP.A.2
    Recognize and represent proportional relationships between quantities.
  • CCSS.Math.Content.7.RP.A.2.a
    Decide whether two quantities are in a proportional relationship.
  • CCSS.Math.Content.7.RP.A.2.b
    Identify the constant of proportionality (unit rate) in tables, graphs, equations, diagrams, and verbal descriptions of proportional relationships.
NY State Science Standards
  • MS-PS4-2
    Develop and use a model to describe that waves are reflected, absorbed, or transmitted through various materials.
CSTA Computer Science Standards
  • 2-CS-02
    Design projects that combine hardware and software components to collect and exchange data.
  • 2-NI-04
    Model the role of protocols in transmitting data across networks and the Internet.
  • 2-DA-07
    Represent data using multiple encoding schemes.
COSMOS concepts to be used for the lab Frequency, voltage, noise, decibel (dB), transmitter amplitude, noise amplitude, environmental noise, health hazards, noise path, receiver, noise source, bandwidth, data rate, signal bandwidth, modulation.
K12 Educational Goals (How the educational goals are achieved through teaching using the experiment, how the topic is connected to the COSMOS concepts used) The educational goal will be achieved by students calculating the rates of change, unit rates, graphing the data, and using its graph to determine proportionality. Students will use the COSMOS Node and GNU Radio Companion Software to collect the data required to complete their calculations.
Short Description and Walk-through of the experiment Day 1:
  • Teacher will explain how radio waves transmit and how electromagnetic waves are susceptible to interference.
  • Students will use the Raspberry Pi (Mobile Node) to measure the signal strength between two walkie talkies from the front of the school steps to the following various places:
    • Subway Station
    • Grocery Store
    • Harlem River Drive
    • School Yard
  • Students will record their data on their worksheet
    • Students will use their data from Table 1 to answer real world mathematical problems.
Day 2:
  1. Students will create a ratio table labeling the amount of salt in water compared to the signal strength from the walkie-talkie.
  2. Students will open the COSMOS Node and open the GNU Radio Companion Software.
  3. Students will put one walkie-talkie in a ziplock bag, close the bag then place that bag into another zip lock bag to ensure walkie-talkie does not get wet. (Be sure to tightly close both bags)
  4. Measure out 10 inches of string and tie the string around the top of the ziplock bag to ensure the bag is closed tightly.
  5. Students will measure out 3 gallons of water to put into each bucket.
  6. Students will place the ruler inside both buckets.
  7. Students will pour ΒΌ cup of salt in bucket A. Wait until the salt is completely dissolved . (2-5 minutes)
  8. Divide students into groups of 4 and assign the following tasks. One task per student.
    1. Student A will hold the walkie-talkie bag by the string and place the bag into the water. (Do not allow the bag to touch the bottom of the bucket or the sides of the bucket.
    2. Student B will push the PTT button on the walkie-talkie and hold it while the bag is in the water (do not open the bag)
    3. Student C will take the maximum decibels to measure the signal strength showing on the GNU Radio.
    4. Student D will write their findings in the table and answer any procedural questions or comments from group members.
  9. Student C will add another 1/4 cup of salt to bucket A.
  10. Students will repeat steps 7a-7d
  11. Student C will add another 1/4 tof salt to bucket A.
  12. Students will repeat steps 7a-7d
  13. Student C will add another 1/4 cup of salt to bucket A.
  14. Students will repeat steps 7a - 7d
  15. Student A will submerge the walkie-talkie bag in water in bucket B (fresh water) while holding the string to ensure the top of the bag (the seal) does not go underwater. (Do not allow the bag to touch the bottom of the bucket or the sides of the bucket.
  16. Student B will push the PTT button on the walkie-talkie and hold it while the bag is in the water. (do not open the bag)
  17. Student C will take the maximum decibels to measure the signal strength showing on the GNU Radio.
  18. Student D will write their findings in the appropriate space and answer any procedural questions or comments from group members.
  19. Students will complete their tables and graph their findings.
  20. Students will decide if the graph is proportional.
Testbed mapping of the experiment The experiment can be extended by executing it into a testbed (ORBIT/COSMOS) through the following steps:
Possible extensions include measuring the signal strength from the nodes to throughout the testbed.

Experiment Execution

Select the appropriate function or the node (Transmitter or Receiver) and press START to begin the experiment. In order to terminate the experiment press STOP.
Transmitter Receiver

Experiment Material

NGSS Lesson Plan
Worksheet

© 2019 COSMOS Project. Created by Brooke Willliams - Arthur Tappan PS/MS 46