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Makerspace Rover: Why Its Sensors Miss Things

Grade 8 waves practice: a makerspace rover's echo sensor and line sensor tests model how materials reflect, absorb or transmit sound and light.

Grade 8ScienceInteractive · Printable

Aligned toMS-PS4-2

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What’s included

Single worksheet
Auto-graded online
1 NGSS standard
Printable answer key
11 questions
Classroom-ready

Details

Format: Interactive · Printable
Grade: Grade 8
Subject: Science
Question types: Fill in the blank, Multiple choice, Circle the answer, Sorting, Short answer

About this worksheet

What students practice

Students use echo sensor results to model whether a material reflects, absorbs or transmits sound.
Students use light sensor readings to model how surfaces reflect, absorb or transmit light.
Students explain why one material can treat light and sound waves differently.

How to use

Before students read, bounce a ball straight at a wall and at a slant to show how a wave reflects. Have partners compare their sorts before the open response.

Curriculum

NGSS standard covered

MS-PS4-2

Model how light and sound waves are reflected, absorbed or transmitted through different materials.

Preview

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Makerspace Rover: Why Its Sensors Miss Things

Use echo and light sensor tests to model how materials reflect, absorb or transmit sound and light.

Test 1: The echo sensor

Read the build notes and study Table 1. Then answer the questions.

Build Notes: The Library Rover

1Every Thursday, the makerspace at the Hollins Branch Library opens for teens. This fall, eighth grader Marisol Nakagawa-Pryor and her mentor, Ms. Zofia Kwarteng, are building a small rover that drives itself around the room without bumping into things. The rover has two sensors that use waves: an echo sensor on its front, which uses sound, and a line sensor under it, which uses light. Ms. Kwarteng said that a good sensor test uses the kinds of objects the rover will meet in the room, such as furniture, cushions, windows and boxes.

2The echo sensor sends out short bursts of ultrasound, sound with a pitch far too high for people to hear. It then listens for an echo. From the time the echo takes to come back, it works out the distance to the object that sent the sound back. If no echo comes back, the sensor shows "no echo," and the rover keeps driving.

3In Test 1, Marisol placed each target 50 cm in front of the echo sensor, with its flat side facing the sensor unless the table says otherwise. The makerspace wall was 120 cm in front of the sensor, behind every target. She could see the wall clearly through the glass pane but not through the plywood board. Table 1 shows what the sensor read for each target.

4The line sensor sits under the rover and points straight down. A small red light shines on the surface, and a light meter right beside it measures how much light comes back up, on a scale from 0 (none) to 100. Marisol's code tells the rover that it is over a line when the reading is below 50, and over plain floor when the reading is 50 or more. The plan is for the rover to follow a path of black electrical tape across a white poster board. Table 2 shows the readings for five surfaces.

5On its first run, the rover started along the tape, but it soon turned and began following the edge of a brown cardboard box lying flat on the poster board, until Marisol picked it up. Marisol wrote down exactly where it went wrong and planned a second round of tests.

Table 1: Echo Sensor Test (target at 50 cm, wall at 120 cm)
Target	Sensor reading
Plywood board	50 cm
Plywood board tilted 45°	no echo
Foam pillow	no echo
Metal window screen	120 cm
Cardboard box	50 cm
Thick wool blanket	no echo
Glass pane	50 cm