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Live online classes
Underline definitions, circle an answer, number a process, and point to the exact area being discussed while the class material remains visible.
For teachers, tutors & trainers
Annotation tool for online teaching
Write over lessons, slides, websites, videos, diagrams, and live demonstrations without leaving the material you are teaching. Move from a quick highlight to a full whiteboard whenever the explanation needs more space.
Essential Pen, Eraser & Screenshot tools · No account required
Keep annotation tools available while your lesson stays on screen.
Annotate liveOver lessons and apps
Precision toolsRuler, compass & more
Built-in whiteboardGrid and backgrounds
Free essentialsNo account to begin
Teach without breaking the flow
Keep the explanation beside the content
Your students see the material and the reasoning together—without repeated switching between the lesson, a separate drawing app, and a screenshot tool.
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Maths and science lessons
Use a ruler, protractor, compass, coordinates, shapes, and a grid whiteboard for explanations that need more precision than freehand drawing.
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Recorded lessons and tutorials
Annotate while demonstrating a topic, capture the marked result, create short GIFs, or use Creator Recorder (Beta) for local screen and microphone recording.
A classroom toolkit on screen
From quick highlighting to detailed teaching
Start with the simplest tool for the moment, then add focus, geometry, board, capture, and recording tools when the lesson calls for them.
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Pen, highlighter, shapes, text, and numbering
Mark important ideas in real time and organise multi-step explanations so students can follow the sequence.
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Whiteboard with grid and backgrounds
Move from annotating a slide to working through a fresh example without opening another application.
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Ruler, protractor, compass, and coordinates
Teach geometry, diagrams, graphs, and measurements with visual tools designed for structured explanation.
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Spotlight, curtain, laser pointer, and timer
Control what students focus on and keep a live lesson or timed practice session moving.
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Screenshots, GIFs, PDF export, and redaction
Turn part of the lesson into a recap, answer sheet, visual explanation, or follow-up resource.
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Local Wi-Fi collaboration (Premium Beta)
Host on Windows and let supported devices on the same local network join a shared annotation session.
Simple class workflow
Use OS Pen during an online lesson
Test your chosen screen-sharing or recording mode once before class so the annotation overlay appears exactly as intended.
Prepare the lesson
Open the slides, website, document, video, or teaching app you plan to explain, then launch OS Pen.
Choose how students will view it
Start your meeting, class, or recording using a capture mode that includes the OS Pen overlay.
Annotate and capture
Write as you teach, erase temporary marks, switch to the whiteboard when needed, and save useful explanations as screenshots.
Online teaching questions
Frequently asked questions
How can I annotate while teaching online?
Open OS Pen's floating toolbar, choose Pen or Highlighter, and write over the lesson, slide, webpage, video, diagram, or other material already visible on your Windows screen.
Can I use a whiteboard and geometry tools for online classes?
Yes. OS Pen includes a whiteboard with background and grid options plus ruler, protractor, compass, coordinates, shapes, text, and numbering tools.
Do I need a touchscreen to teach with OS Pen?
No. You can annotate with a mouse or trackpad. A touchscreen or compatible stylus can make handwriting feel more natural, but it is optional.
Will students see the annotations in my online meeting?
That depends on the meeting or recording app's capture mode. Choose a screen-sharing mode that includes overlays and test it before class. Sharing the full display is often the clearest option.
Can I try the annotation tools free?
Yes. Pen, Eraser, and Screenshot are available as free essentials without an account. A verified-email trial unlocks the complete toolset without requiring a credit card.
Make online lessons easier to follow
Begin with free essential annotation tools, then compare plans when you need the complete teaching toolkit.