**Course Title:** Introduction to Programming with Scratch **Section Title:** User Input and Sensing **Topic:** Introduction to sensing blocks: Detecting keyboard and mouse inputs **Introduction** In this topic, we will explore the sensing blocks in Scratch, which enable our projects to detect and respond to user input from the keyboard and mouse. Sensing blocks are a powerful tool in Scratch, allowing us to create interactive and engaging projects that respond to user input. **What are Sensing Blocks?** Sensing blocks are a type of block in Scratch that allow our projects to detect and respond to various inputs, such as keyboard and mouse input, sounds, and video motion. These blocks can be used to create projects that are more interactive and engaging, such as games, simulations, and interactive stories. **Detecting Keyboard Inputs** The sensing blocks in Scratch allow us to detect keyboard inputs, such as arrow key presses, space bar presses, and alphabetical key presses. To detect keyboard inputs, we can use the following blocks: * `key [space v] pressed` block: This block returns `true` if the space bar is pressed and `false` otherwise. * `key [left arrow v] pressed` block: This block returns `true` if the left arrow key is pressed and `false` otherwise. * `key [right arrow v] pressed` block: This block returns `true` if the right arrow key is pressed and `false` otherwise. * `key [up arrow v] pressed` block: This block returns `true` if the up arrow key is pressed and `false` otherwise. * `key [down arrow v] pressed` block: This block returns `true` if the down arrow key is pressed and `false` otherwise. We can use these blocks in combination with other blocks to create interactive projects that respond to keyboard input. For example, we can use the `key [space v] pressed` block to create a project that makes a sprite jump when the space bar is pressed. **Example: Creating a Sprite that Jumps when the Space Bar is Pressed** To create a sprite that jumps when the space bar is pressed, we can use the following blocks: * `when green flag clicked` block: This block starts the project when the green flag is clicked. * `forever` block: This block runs the blocks inside it forever. * `if` block: This block runs the blocks inside it if the condition is `true`. * `key [space v] pressed` block: This block returns `true` if the space bar is pressed and `false` otherwise. * `change y by 10` block: This block changes the y position of the sprite by 10 pixels. Here is an example of how we can use these blocks to create a sprite that jumps when the space bar is pressed: ``` when green flag clicked forever if <key [space v] pressed?> change y by 10 end end ``` **Detecting Mouse Inputs** The sensing blocks in Scratch also allow us to detect mouse inputs, such as mouse clicks and mouse movements. To detect mouse inputs, we can use the following blocks: * `mouse down?` block: This block returns `true` if the mouse is clicked and `false` otherwise. * `mouse x` block: This block returns the x position of the mouse. * `mouse y` block: This block returns the y position of the mouse. We can use these blocks in combination with other blocks to create interactive projects that respond to mouse input. For example, we can use the `mouse down?` block to create a project that changes the color of a sprite when the mouse is clicked. **Example: Creating a Sprite that Changes Color when the Mouse is Clicked** To create a sprite that changes color when the mouse is clicked, we can use the following blocks: * `when green flag clicked` block: This block starts the project when the green flag is clicked. * `forever` block: This block runs the blocks inside it forever. * `if` block: This block runs the blocks inside it if the condition is `true`. * `mouse down?` block: This block returns `true` if the mouse is clicked and `false` otherwise. * `change color by 10` block: This block changes the color of the sprite by 10 hues. Here is an example of how we can use these blocks to create a sprite that changes color when the mouse is clicked: ``` when green flag clicked forever if <mouse down?> change color by 10 end end ``` **Conclusion** In this topic, we have learned how to use sensing blocks to detect keyboard and mouse inputs in Scratch. We have also created two interactive projects that respond to keyboard and mouse input. Sensing blocks are a powerful tool in Scratch, allowing us to create interactive and engaging projects that respond to user input. **What's Next?** In the next topic, we will learn how to use the `ask` and `answer` blocks to get user input. **Practice Exercises** 1. Create a project that makes a sprite move left when the left arrow key is pressed. 2. Create a project that changes the color of a sprite when the mouse is clicked. 3. Create a project that makes a sprite jump when the space bar is pressed and changes direction when the mouse is moved. **Resources** * Scratch Documentation: Sensing Blocks (https://en.scratch.mit.edu/docs/interface/sensing-blocks/) * Scratch Forums: Sensing Blocks (https://scratch.mit.edu/discuss/topic/2457/) **Leave a comment or ask for help** If you have any questions or need help with this topic, please leave a comment below.