Classroom Screen Sharing: Broadcast Teacher Display to Student Devices Offline

In school computer labs, university lecture halls, and corporate training centers, teachers frequently need to broadcast their desktop display onto dozens of student monitors. However, relying on commercial cloud meeting software (Zoom, Teams, Google Meet) in an educational environment creates significant roadblocks:

1. Bandwidth Saturation: Streaming 30 or 40 individual high-definition video feeds through external internet connections quickly exhausts school internet pipes.
2. Student Account & Sign-in Fatigue: Requiring every primary or secondary school student to create an account, enter email addresses, and manage passwords wastes valuable instructional time.
3. Expensive Per-Seat Licensing: Commercial classroom management tools (LanSchool, Netop Vision) cost thousands of dollars annually in recurrent subscription fees.

ScreenTask provides an open-source, 100% free solution. By turning the instructor’s PC into a lightweight local HTTP streaming server, any student device on the local network—whether a Windows desktop, Chromebook, iPad, or Android tablet—can view the teacher’s screen in real time through their standard web browser.

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Why ScreenTask is Built for Classrooms & Labs

Challenge with Cloud Tools	ScreenTask Offline LAN Solution
Burns school internet bandwidth	0 KB internet data used (Local LAN only)
Student sign-in and software installs	Zero student apps (Runs in Chrome, Safari, Edge)
High recurrent software licensing costs	100% Free & Open-Source (GNU GPL v3)
Incompatible student devices	Cross-platform (Windows, Mac, Linux, iOS, ChromeOS)
Cloud downtime during outages	Works even if the school internet is completely down

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Step 1: Prepare the Teacher’s Workstation

1. Download the portable version of ScreenTask from the ScreenTask Download Hub onto the teacher’s PC.
2. Ensure the teacher PC is connected to the classroom LAN (via Wi-Fi or classroom Ethernet wall jack).
3. Open ScreenTask.exe.
4. From the IP dropdown, select the teacher workstation’s local classroom IP (e.g., 10.10.4.25 or 192.168.1.100).
5. Choose your target Port (default: 7070).
6. Set the Refresh Rate to 500 ms (2 frames per second) or 1000 ms (1 frame per second). For coding lectures, presentations, and mathematics problems, 1–2 FPS keeps network overhead exceptionally low.
7. Click Start Server.

[!TIP] Classroom Display Clarity: In Windows Settings $\rightarrow$ System $\rightarrow$ Display, consider lowering your desktop display resolution to 1920x1080 (1080p). This ensures text and diagrams remain readable on smaller student laptop screens and tablets.

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Step 2: Distribute the Viewing URL to Students

Because ScreenTask serves pure HTML5, students do not need to download software, install browser extensions, or create accounts:

Method A: Write the URL on the Whiteboard

Write the local address clearly on the classroom board:

http://10.10.4.25:7070

Method B: Display a Quick QR Code

Generate a simple offline QR code of your local URL (e.g. using any free offline QR generator) and project it onto the classroom projector. Students with iPads or smartphones can scan the QR code with their camera to immediately open the stream in Safari or Chrome.

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Step 3: Prevent Unauthorized Viewers with Password Protection

If your classroom shares a Wi-Fi network with other classrooms or neighboring offices, you can prevent students from outside your class from tuning in:

1. In ScreenTask, check the Password Protection option.
2. Enter a temporary session password (e.g., Room204).
3. When students navigate to your URL, their browser will prompt them for the password before rendering the live display.

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Network Performance: Scaling to 30+ Student Devices

Because ScreenTask uses standard HTTP requests, local 100 Mbps or 1 Gbps classroom network switches and commercial Wi-Fi access points (Ubiquiti, Cisco, Aruba) can easily handle 30–50 concurrent student browser connections:

• At 1 FPS (1000 ms): Each frame averages 80–120 KB JPEG compression. 30 concurrent viewers consume only ~2.5–3.5 MB/s of local LAN capacity—well within standard Wi-Fi router limits.
• For Video Demonstrations: If you need to demonstrate fluid animations or video playback, connect the teacher PC via a physical Ethernet cable to minimize wireless collision.

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Related Guides & Resources

• Windows 10 Setup & Firewall Configuration
• How to Stream PC Screen to Phone & Tablet Browsers
• Cross-Platform LAN Screen Sharing (Mac, Linux, Chromebooks)
• Download ScreenTask for School Labs