informatika kelas 9 bab 7 Algoritma dan pemrograman, bilangan prima dengan scratch dan blockly

Introduction

This tutorial focuses on programming prime numbers using Scratch and Blockly, as presented in the video "Informatika Kelas 9 Bab 7 Algoritma dan Pemrograman." Understanding prime numbers and the algorithms to identify them is essential in computer science and programming. This guide will walk you through the necessary steps to create a program that can determine prime numbers using both Scratch and Blockly.

Step 1: Understanding Prime Numbers

Before diving into programming, it's important to grasp the concept of prime numbers.

• A prime number is a natural number greater than 1 that has no positive divisors other than 1 and itself.
• Examples of prime numbers: 2, 3, 5, 7, 11, 13, etc.
• The first step in programming is to define a function that can check if a number is prime.

Step 2: Setting Up Your Scratch Environment

To start coding in Scratch, follow these steps:

1. Go to the Scratch website or open your Scratch application.
2. Create a new project by clicking on "Create."
3. Familiarize yourself with the Scratch interface, including the blocks palette, stage area, and script area.

Step 3: Creating the Prime Number Algorithm in Scratch

Now, you will create the algorithm to check for prime numbers in Scratch.

1. Define a Variable:

   • Create a variable named "number" to store the number you want to check.
   • Create another variable named "isPrime" and set it to true.

2. Set Up the Loop:

   • Use a loop to iterate from 2 to the number you are checking.
   • If the number is divisible by any number in this range, set "isPrime" to false.

3. Final Check:

   • After the loop, use an if-else block to display whether the number is prime based on the value of "isPrime."

Example Scratch blocks for the algorithm:

when green flag clicked
set [number v] to (input number)
set [isPrime v] to [true]
if <(number) < 2> then
    set [isPrime v] to [false]
else
    repeat (number - 2)
        change [i v] by (1)
        if <(number) mod (i) = 0> then
            set [isPrime v] to [false]
        end
    end
end
if <(isPrime) = [true]> then
    say [This number is prime]
else
    say [This number is not prime]
end

Step 4: Transitioning to Blockly

After creating the prime number checker in Scratch, you can transition to Blockly for a different visual programming experience.

1. Access Blockly: Open the Blockly environment, which can be found on various online platforms or integrated into educational tools.

2. Create a New Project: Start a new project in Blockly.

3. Build the Same Algorithm:

   • Use similar logic as in Scratch, utilizing Blockly’s blocks to create variables, loops, and conditionals.

4. Code Example in Blockly:

   • Drag and drop blocks to replicate the Scratch logic. Ensure you set the same flow for checking if a number is prime.

Conclusion

In this tutorial, you learned how to program a prime number checker using Scratch and Blockly. By understanding the algorithm behind prime numbers and implementing it in two different programming environments, you enhanced your programming skills.

Next steps could include:

• Experimenting with larger numbers.
• Modifying the program to list all prime numbers within a range.
• Exploring more advanced algorithms for prime number generation.

Keep practicing and exploring the world of algorithms and programming!