How to Use Sensing Blocks in Scratch | Scratch Programming for Beginners | Live Coding with Examples

Introduction to Sensing Blocks in Scratch

In today's session, we're diving deep into one of the most powerful features of Scratch — Sensing Blocks. These blocks allow your projects to interact with the world, detect touches, respond to colors, receive user input, sense sound levels, track mouse and keyboard actions, and even keep time!

Whether you're building a game, animation, or quiz — sensing blocks help bring your Scratch creations to life by making them truly interactive.

In this live coding tutorial, we'll walk you through each sensing block with real-time examples, show you how to use them effectively, and share tips for combining them into creative projects.

What You Will Learn:

This comprehensive guide teaches you how to:

• ✅ Detect sprite interactions using Touching and Color Touching blocks
• ✅ Take and display user input using Ask and Answer blocks
• ✅ Track keyboard and mouse actions
• ✅ Measure distance between sprites and objects
• ✅ Use loudness, timers, backdrops, current date/time, and username sensing
• ✅ Create dynamic and personalized experiences
• ✅ Build interactive games and projects

This project is perfect for beginners and intermediate Scratch users who want to learn Scratch programming and how to make interactive projects in Scratch.

What are Sensing Blocks in Scratch?

Sensing blocks are a category of blocks in Scratch (colored cyan) used to detect different types of information: interaction (touch, mouse, keyboard), environment (color, backdrop), input (ask / answer), time, distance, loudness, etc.

In Scratch 3.0, there are 18 sensing blocks:

3 Stack blocks (these do something when run, and are not just reporters or booleans):

• ask [] and wait
• reset timer
• set drag mode [draggable / not draggable]

5 Boolean blocks (return true/false):

• touching (…) ?
• touching color [color]?
• color [color1] is touching [color2]?
• key [key] pressed?
• mouse down?

10 Reporter blocks (return a value, number, or string):

• distance to (…)
• answer
• mouse x
• mouse y
• loudness
• timer
• [variable] of [sprite]
• current [year / date / month / day / hour / minute / second]
• days since 2000
• username

How to Use Sensing Blocks — Scenarios & Code Examples

1. Detect Touching (Sprite / Edge / Object)

Scenario: A sprite changes its costume when it touches another sprite or the stage edge.

Blocks to use: if or if

Example Code:

Enhancement: You can add sounds, change color, or bounce instead.

2. Touching Color, Color is Touching Color

Scenario: If a sprite touches a specific color (e.g. red), then add or subtract score. Or, if a part of sprite's color touches another object's color.

Blocks: touching color [#FF0000]?, color [#00FF00] is touching [#0000FF]?

Example Code:

Enhancement: Use different colors for different sprites; dynamically pick colors with color picker.

3. Measuring Distance

Scenario: Make a sprite chase another sprite, or avoid when close.

Block: distance to [Sprite2] or distance to (mouse pointer)

Example Code:

4. Asking & Waiting for User Input (Ask – Answer)

Scenario: Quiz game asking for user's name, and then greeting them.

Blocks: ask [What is your name?] and wait, answer

Example Code:

Enhancement: Input validation (e.g., ensure not blank), or ask multiple questions in a quiz with scoring.

5. Key Pressed & Mouse Down

Scenario: Control sprite movement via arrow keys; or perform action when mouse is clicked.

Blocks: key [left arrow] pressed?, mouse down?

Example Code:

6. Mouse X, Mouse Y & Drag Mode

Scenario: Track where the mouse is; or allow dragging sprite.

Blocks: mouse x, mouse y, set drag mode [draggable]

Example Code:

Or, tracking:

7. Loudness (Microphone Input)

Scenario: Make sprite respond to loudness, e.g. raise its costume size when you shout.

Blocks: loudness

Example Code:

8. Timer, Reset Timer

Scenario: In a game, measure time taken; create a countdown or stopwatch.

Blocks: timer, reset timer

Example Code:

9. Backdrop Sensing

Scenario: Change behavior depending on which backdrop is showing (scene changes).

Blocks: backdrop [name / number]

Example Code:

10. Date, Time & Username

Scenario: Show current year/month/date; personalize with username.

Blocks: current [year], current [month], current [date], username

Example Code:

Enhancement Features

To make your Scratch projects using sensing blocks more engaging, here are enhancements you can add — along with code snippets:

1. Multiple Levels / Scenes

Use backdrop sensing to switch between levels; conditionally trigger when backdrop changes.

2. Scoring & Lives System

Combine sensing blocks (touching, color) with variables to track score / lives.

3. Adaptive Difficulty

Use timer and distance blocks to make the game harder as time increases (e.g. enemies move faster, thresholds get stricter).

4. User-Driven Customization

Ask user preferences, username, color choices; use those to adapt game look, sprite color.

5. Sound / Microphone-Based Interaction

Use loudness to trigger animations; for example, sprite jumps when you shout, or blinks when sound crosses threshold.

6. Mouse Tracking / Drag & Drop

Use mouse x / mouse y with go to or set drag mode to allow drag-drop or pointer-following sprite.

Complete Code Example: A Simple Game Putting It All Together

Here's a full little game idea combining many sensing blocks. Name it Color Dodger:

• Sprites: Player (controlled by arrow keys), Bad Blocks (randomly falling), Background / Backdrop changes for levels
• Features: Score, Lives, Timer, Color detection, Key press, Touching, Ask for player name

Main Script (Player Sprite):

BadBlock Sprite Script:

Enhancements:

• Use touching color to avoid certain colored zones
• Use headphones / loudness to let player shout to freeze blocks temporarily
• Use mouse down? to shoot or interact

Conclusion

And that wraps up our deep dive into Sensing Blocks in Scratch! From detecting touch, color, and distance, to capturing keyboard input, tracking mouse movement, using the microphone, and even reacting to the current time and user info — you now have a solid understanding of how sensing blocks make your Scratch projects smart and responsive.

✅ Whether you're working on a game, an interactive quiz, or a custom animation, sensing blocks give you the power to make your projects come alive by reacting to the world around them.

Here's a quick recap of what you've learned:

• How to detect sprite interactions using "Touching" and "Color Touching" blocks.
• Taking and displaying user input using "Ask and Wait" and "Answer" blocks.
• Tracking keyboard and mouse actions.
• Measuring distance between sprites and objects.
• Using loudness, timers, backdrops, current date/time, and username sensing to create dynamic and personalized experiences.