#### – Determining how the Wheels Rotate

According to the Steering Setting –

**Please find a printable version of this page HERE.**

#### Task Description

The learning goal of Part 1 is to understand how the steering in the <Move> Programming Block varies the left and right wheel rotations of the robot. The directionality of the turn helps students gain a spatial sense of positive and negative numbers.

#### Materials Needed

- Basic Lego Mindstorms EV3
**robot**, built according to the instructions - Lego Mindstorms Education EV3 classroom
**software**, installed on a laptop or tablet **Recording Sheet**for Part 1, available at http://stem-education.ca/files/SteeringRecordingsheet_2020Part1.pdf

(a version with the older EV3 Education program is available here: http://stem-education.ca/files/SteeringRecordingsheet-oldEV3_2020.pdf)

#### Note for Teachers

When getting started, it is always prudent to show students how to save their files. We encountered a few tears when students lost their programs on their iPad or computer.

Note in this part of the task the robot is **held above the ground** so the wheels do not touch the floor or surface.

Encouraging students to place the arrow-like wheel holder in an upwards position will help facilitate accurate observations.

The recording sheet provides detailed instructions. Basically, the students are observing and recording the direction and amount of wheel rotations according to variations in the steering setting of the <Move> Programming Block, i.e., -100, -75, -50, -25, 0, 25, 50, 75, and 100.

Your students may start to see the pattern quite quickly. The pattern is symmetrical around 0, where the robot turns clockwise with positive steering and counterclockwise with negative steering. The number of rotations for the left and right wheel is reversed. Encourage students to predict before testing their ideas with the robot.

#### Instructions, Steps and Programming for Part 1

**Please find a printable version of the Recording Sheet HERE.**

- Drag and drop a <Move> block onto the programming chain.
- Enter 100 in the <Move> bubble.
**Leave the number of wheel rotations as “1”**. Leaving the number of wheel rotations at 1 is necessary for consistent results to help students to identify the pattern. - Download the program to the robot.
- Watch the right wheel. Run the program. Hint: Line up the right white wheel holder with the top support.
- Which direction does the right wheel travel? Draw an arrow on the worksheet to indicate the direction.
- How many rotations did the right wheel make? Enter the number of rotations on worksheet.
- Repeat Steps 5 and 6 for the left wheel.
- Draw the direction the wheel travels in the worksheet.
- Repeat all the steps for 75, 50, 25, 0, -25, -50, -75, and -100.

#### Mathematics Learning

Part 1 of the task involves **observation** and **data collection**, **interpretation of data**, **negative numbers**, and **fractions**. For Grade 4’s, integers are not introduced until later. However, in Canada where we live, the cold weather provides prior experiences of negative numbers for even the youngest children (e.g., -20^{o} Celsius means cold).

As well, the robot’s motion is coherent with an **intuitive number line understanding** where increasing positive numbers move forward, and increasing negative numbers move backwards. Positive wheel rotations in the <Move> Programming Block result in forwards motion and vice versa for negative numbers. In our experience, an initial brief explanation of positive and negative numbers with a number line example is grasped quickly.

To reinforce and scaffold **spatial understandings of numbers**, it is useful to provide a vertical and horizontal number line representation of the fractions to help students visualize number as position or location. Note that the vertical and horizontal number lines are also components for understanding Part 3 of this task.

As you can see from the Recording Sheet above, students are measuring the rotation of the wheels, recording direction along with positive and negative numbers (spatial understanding of number), ordering fractions and whole numbers (extending understanding of fraction equivalence and ordering), representing data, and finding patterns and structures for interpretation.

#### Go To

- Move Steering Main Page
- Part 2 – Describing and Modeling the Robots’ Turns According to the Steering Setting
- Part 3 – Modeling Steering Differential with Fractions and Percentages

© 2020 Dr. Krista Francis & Stefan Rothschuh

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