Download

01 The overlay

scroll to fly · drag to roam · draw anywhere

Windows 10 & 11 · v1.3.0

Explain it on the screen, not beside it.

A transparent overlay for teaching. Draw, highlight, drop in shapes, graph and time the section — on top of the PDF, call or video you are already using.

Download for Windows Portable .exe

64-bit · works offline · no account

The overlay annotating a practice test in a PDF viewer.
Actual screen, mid-lesson

Video goes here

Drop assets/lesson.mp4 in and uncomment the tag in index.html

Thirty seconds of a real explanation, start to finish.

Four ink tools,
five shapes,
eight colours.

Pen, marker, eraser and text. Lines, arrows, rectangles, circles, triangles — plus cylinders, spheres, cones, pyramids and prisms for the volume questions.

PMET   LARCG

The Drawing flyout: pen, marker, eraser, text.
Drawing
The 3D Shapes flyout.
3D shapes
Style and colour panel.
Style & colour

This board takes ink.

The toolbar on the left is the real thing. Pick a colour and draw — on this card, on the screenshots, anywhere on the board. Esc wipes it.

draw across me →

V = πr²h

Exact160 π

Decimal502.65

drag to orbit

The 3D Shapes flyout.

WebGL is off — here is the tool itself.

The same solids the app stamps on screen, rendered live. Volumes match its calculator.

Four things you
would otherwise
alt-tab for.

Calculator solving circle area for radius 3: 9 pi and 28.27433.
Calculator — exact and decimal
The formulas panel.
Formula reference
The graphing panel.
Graphing, in the overlay
The lesson timer at 10:00.
Lesson timer

One key per tool.

CtrlShiftA
overlay on / off
CtrlShiftQ
quit
Esc
clear everything
PMET
pen, marker, eraser, text
LARCG
line, arrow, rect, circle, triangle
USOYB
cylinder, sphere, cone, pyramid, prism

Switch input off and every click passes through to the app underneath — your ink stays on screen.

Get it.

Not code-signed yet, so SmartScreen may warn on first run: More info → Run anyway.

© 2026 slsk · Windows only, for now