WEBVTT 00:00.000 --> 00:05.000 Visual programming with Scratch 00:05.000 --> 00:10.000 In this lesson, we will understand the Scratch interface and its main components. 00:10.000 --> 00:14.000 How to use sequence, selection, and iteration blocks. 00:14.000 --> 00:19.000 How to implement algorithms with variables and events. 00:19.000 --> 00:22.000 Introduction to Scratch 00:22.000 --> 00:24.000 Ever wanted to make your own game? 00:24.000 --> 00:29.000 Well, today we're going to learn about visual programming with Scratch. 00:29.000 --> 00:34.000 With Scratch, you build code by snapping blocks together like digital Legos. 00:34.000 --> 00:38.000 Today, we'll create a game where a spaceship catches falling stars. 00:38.000 --> 00:44.000 Each catch adds to your score and the game lasts 10 seconds. 00:44.000 --> 00:47.000 First, get to know the Scratch interface. 00:47.000 --> 00:50.000 The stage where the game runs. 00:50.000 --> 00:53.000 The sprites pane. 00:53.000 --> 00:55.000 The blocks palette. 00:55.000 --> 00:58.000 And the scripts area where you build. 00:58.000 --> 01:02.000 Delete the default cat. 01:02.000 --> 01:05.000 Pick a space backdrop. 01:05.000 --> 01:09.000 Add a spaceship sprite for the player. 01:09.000 --> 01:13.000 And add a star sprite to catch. 01:13.000 --> 01:19.000 This ordered setup is called sequence, our first programming concept. 01:19.000 --> 01:22.000 Events and iteration. 01:22.000 --> 01:26.000 Now, let's program the player controls for our spaceship. 01:26.000 --> 01:29.000 First, drag the block when green flag clicked. 01:29.000 --> 01:32.000 This tells the game to start when we press the green flag. 01:32.000 --> 01:41.000 Next, set the spaceship starting position using go to x0, y-120. 01:41.000 --> 01:44.000 This places it at the bottom of the screen. 01:44.000 --> 01:46.000 Now, add a forever loop. 01:46.000 --> 01:50.000 This means the game will keep checking for player input the whole time. 01:50.000 --> 01:53.000 Inside the loop, use an if block. 01:57.000 --> 02:02.000 If the right arrow key is pressed, change x by 10. 02:02.000 --> 02:08.000 This moves the spaceship to the right, then add another of block. 02:08.000 --> 02:12.000 If the left arrow key is pressed, change x by negative 10. 02:12.000 --> 02:15.000 This moves the spaceship to the left. 02:15.000 --> 02:21.000 Together, this code lets the player move the spaceship left and right using the arrow keys. 02:21.000 --> 02:26.000 Now, let's program the star so it keeps falling from the top of the screen. 02:26.000 --> 02:31.000 We start with when green flag clicked, so the star's code runs when the game begins. 02:31.000 --> 02:34.000 Next, we add a forever loop. 02:34.000 --> 02:36.000 This makes the star keep repeating its action. 02:36.000 --> 02:41.000 Inside the loop, we drag in the go to xy block. 02:41.000 --> 02:46.000 For the x value, we insert a pick random negative 200 to 200 block. 02:46.000 --> 02:50.000 This makes the star appear at a different random spot across the top each time. 02:50.000 --> 02:56.000 For the y value, we set it to 180, so the star always starts from the top of the stage. 02:56.000 --> 02:59.000 We use show to make the star visible. 02:59.000 --> 03:02.000 Now we add a repeat until loop. 03:02.000 --> 03:07.000 Inside it, we place an or operator. 03:07.000 --> 03:12.000 On one side, we check touching player. 03:12.000 --> 03:19.000 And on the other, we check if the star's y position is less than negative 170. 03:19.000 --> 03:27.000 While neither condition is true, we use change y by minus 10 to make the star fall step by step. 03:27.000 --> 03:37.000 When the star either touches the player or goes past the bottom, the loop stops and we use hide to make the star disappear. 03:37.000 --> 03:44.000 Because this is inside a forever loop, the star keeps coming back at the top and falling again. 03:44.000 --> 03:47.000 Variables and operators. 03:47.000 --> 03:51.000 Now we add variables to keep track of the score and the timer. 03:51.000 --> 03:55.000 First, we click on the variables category, then select make a variable. 03:55.000 --> 03:59.000 We name it score and make sure it's set for all sprites. 03:59.000 --> 04:01.000 A score monitor appears on the stage. 04:01.000 --> 04:06.000 Next, we make another variable and name it timer. 04:06.000 --> 04:08.000 Now let's use these variables. 04:08.000 --> 04:10.000 We go back to the star's code. 04:10.000 --> 04:16.000 After the repeat until loop, but before the hide block, we insert an if block. 04:16.000 --> 04:19.000 Inside it, we check touching player. 04:19.000 --> 04:28.000 If true, we use change score by 1 to increase the score and we also add start sound collect for a fun effect. 04:31.000 --> 04:34.000 Next, we program the timer. 04:34.000 --> 04:37.000 For this, we click on the stage and add a new script. 04:37.000 --> 04:40.000 We start with when green flag clicked. 04:40.000 --> 04:45.000 Then we set score to 0 and timer to 10. 04:46.000 --> 04:48.000 We add a repeat 10 loop. 04:48.000 --> 04:54.000 Inside it, we use wait 1 second and then change timer by minus 1. 04:54.000 --> 04:57.000 This counts down the time step by step. 04:57.000 --> 05:02.000 When the loop ends, we use stop all so the game finishes after 10 seconds. 05:02.000 --> 05:09.000 This way our variables track the score and limit the game time, making the game both challenging and fun. 05:10.000 --> 05:15.000 Debugging, testing and sharing. 05:15.000 --> 05:18.000 Click the green flag to test your game. 05:18.000 --> 05:24.000 If something goes wrong, like the star getting stuck, the score not increasing or the timer not stopping, 05:24.000 --> 05:28.000 check your loops, conditions and where the script is placed. 05:28.000 --> 05:32.000 When it works, share your game online or save it. 05:32.000 --> 05:38.000 Let friends play, ask if it's too easy or hard, then adjust speed or timer based on feedback. 05:39.000 --> 05:44.000 Scratch makes learning programming easy, interactive and creative, 05:44.000 --> 05:49.000 helping you build logical thinking and problem solving skills for the future.