[RL86] Grade 8 - Session 6

M3D RoboticsLab RoboticsLab Grade 8
1

Session: Programming with Loops – Creating an Interactive Calculator with Robotics

Duration: 60 minutes

Learning Objectives:

In this session, students will:

  1. Understand and implement for loops to repeat a set of instructions and manage user input.
  2. Practice error-checking with loops to ensure valid user responses.
  3. Develop a basic calculator that uses Web BLE to gather user input for mathematical operations.
  4. Use conditional statements to handle different operations (addition, subtraction, multiplication, division).
  5. Add interactive components by making the robot respond with emojis, notifications, and movement based on calculations.
  6. Engage in real-life examples and discussions to understand how repeated instructions and error handling are used in various applications.

Equipment Required:

  • M3D Robotics kit with Web BLE support
  • Laptop or PC with Arduino IDE
  • USB/OTG cables to connect robots
  • Projector for live code demonstration (optional)

1. Introduction to For Loops and Repeating Commands (10 minutes)

Starting Discussion:

You may start by asking:

“Have you ever tried doing something repeatedly, like practicing a new dance move or saying a word over and over? Why might it be helpful for our robot to repeat instructions automatically?”

Lead into the concept:

“Just like how we repeat actions to get better, we can make the robot repeat instructions automatically using a for loop. This lets us code a set of instructions once, but have them repeated as many times as we want.”

Real-Life Examples of Loops:

“Imagine an elevator that opens and closes its doors for each floor. It repeats a set of actions every time it reaches a floor. That’s similar to how a for loop works in programming.”

Basic Code Explanation:

  • Introduce the basic format of a for loop, explaining each part:
    for (int i = 0; i < 5; i++) {
    go.forward(10); // Moves the robot forward 10 cm, 5 times
}

You may ask students:

“What do you think i < 5 means in this code? Why would it stop the loop after 5 repetitions?”

Explanation: Guide them to understand that this tells the robot to repeat moving forward only 5 times.

2. Using Loops for Error-Checking with User Prompts (10 minutes)

Discussion on Input Validation:

You may ask:

“Have you ever used a form online that told you to re-enter information if something was wrong? What if we needed our robot to keep asking a question until it got a correct answer?”

Lead into the idea:

“We can use a for loop to keep prompting the user to enter a correct response, such as choosing one of the math operators (+, -, *, /). This lets us make sure the user only enters something we can use in our program.”

Example Code to Prompt User for Valid Operator:

  1. Introduce code with a loop that keeps asking the user to enter one of the four operators until they input a valid one.
    String operator;
for (;;) { // This loop continues until it receives a valid operator
    operator = remote.askString("Choose an operation: +, -, *, or /");
    if (operator == "+" || operator == "-" || operator == "*" || operator == "/") {
        break; // Exit the loop if the input is valid
    } else {
        display.text("Please enter a valid operator!"); // Prompts again if input is invalid
    }
}

Question to Students:

  • “Why do you think we have the break command here? What would happen if we removed it?”

Explanation: This allows students to see that the loop would keep running without the break statement, showing the importance of having a way to exit the loop once the input is correct.

3. Building the Calculator Step-by-Step (25 minutes)

Step 1: Getting User Inputs for the Numbers

  • Guide students to write code that prompts the user for two numbers. Explain each line carefully and ask guiding questions.
    int num1 = remote.askInt("Enter the first number:");
int num2 = remote.askInt("Enter the second number:");

Ask students:
“What do you think would happen if we didn’t ask for these two numbers? Would the robot be able to calculate anything?”

Step 2: Writing Conditional Statements for Each Operator

  • Explain how the program uses conditional statements to perform the operation the user selected.
    int result;
if (operator == "+") {
    result = num1 + num2;
    display.text("Result: " + String(result)); 
} else if (operator == "-") {
    result = num1 - num2;
    display.text("Result: " + String(result));
} else if (operator == "*") {
    result = num1 * num2;
    display.text("Result: " + String(result));
} else if (operator == "/") {
    result = num1 / num2;
    display.text("Result: " + String(result));
}

Discussion Questions:

  • “Why do we need to check for each operator individually?”
  • “What would happen if we skipped one of these checks?”

Explanation: Help students understand that without checking each operator individually, the program wouldn’t know which calculation to perform.

Step 3: Making the Robot Move Based on Result

  • Explain how to make the robot move according to the calculation’s result.
    go.forward(result); // Robot moves forward by the result in cm

Ask students:

“If the result is 20, how far will the robot go? What if the result is smaller or larger? What if it is negative?”

Explanation: This step visually reinforces the concept of using calculated results to control actions.

4. Testing and Debugging with Real-Time Interaction (10 minutes)

Activity:

  • Have students test their code by entering different operators and numbers. Encourage them to test for edge cases (like entering invalid operators) to see how the error-checking works.

Teacher’s Role:

  • Walk around to support students, answer questions, and help troubleshoot any issues.

5. Wrap-Up and Reflection (5 minutes)

Reflection Questions:

  • “How did the for loop help us make this calculator user-friendly?”
  • “Why was it important to have the loop repeat the operator question if it was incorrect?”
  • "What other tasks could we use loops and conditionals for with our robot?”

Cool Fact:

“Did you know? Loops and conditionals are used in real-world applications like online shopping forms, which automatically check your information, and self-driving cars, which use loops to keep checking their environment for safety."

Learning Outcome:

By the end of this session, students will understand how to use loops and conditionals to create interactive programs, enabling them to build a simple calculator that interacts with them through Web BLE. They’ll have a solid grasp of for loops, error-checking, and conditional logic, and see the practical use of programming to create systems that respond dynamically to user input.