Find the Hidden Letter





Name of Activity Find the Hidden Letter
Author STOMP
Keywords 1 Hour Total, NXT, datalogging, hidden letter, alphabet, light sensor, data, 4-6, 7-9
Subject NXTs
Grade Level 4, 5, 6, 7, 8, 9+
Time 1 Hour Total
Brief Description Students will use the NXT/RCX datalogging feature to identify a hidden
letter of the alphabet using light sensor data.
Lesson Objectives: To program an NXT/RCX vehicle to collect data.
To analyze data and come up with a solution.
Materials Needed: NXT/RCX kits.
MINDSTORMS 2.0 with datalogging
capabilities orROBOLAB investigator.
Large print out of a letter of the alphabet.
Should cover a 8 1/2 by 11 sized paper.
Preparation and Set Up: Set up the hidden letter on the floor or on a table, but make sure that it cannot be seen.
Have pre-built NXT/RCX vehicles or allow students to construct their own.
Set up computer with MINDSTORMS 2.0 or ROBOLAB Investigator.
Necessary Background Datalogging is used to collect data from the sensors on the NXT vehicle.
This data an then be uploaded on to a computer an analyzed.
The light sensor will be used in this activity to collect information
about the color changes of the hidden letter.
  1. Attach a light sensor to your NXT/RCX car so that it is pointed at the floor. Wire this to port 1.
  2. Open the datalogging feature in MINDSTORMS 2.0, or open Investigator 2 in ROBOLAB.
  3. Program your vehicle to collect light data as it drives (see picture attached). You may need to adjust the power level depending on how fast your car drives over the hidden letter.
  4. Have the car drive across the letter at least 5 times in different places.
    1. This can be done by having your car drive across the letter one way three times, each time moving the car down a few inches, then doing the same thing but in a different orientation.
  5. Upload your data by clicking on the upload button of MINDSTORMS datalogging or in ROBOLAB investigator.
  6. Examine the data for peaks and valleys indicating light or dark areas. From these graphs have students try to decipher what letter the car drove over.
  7. Allow student to continue testing and then to guess what the hidden letter is.
  8. You may want to have a few hidden letters so that students can try this activity several times.
Extensions: Limit the number of times you allow a car to drive over a letter.

Add a second light sensor to collect more data.

Reference 1

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