How to teach biology online on a whiteboard: an osmosis lesson, step by step

What a biology tutor does on a whiteboard

In a January 2026 thread on r/TutorsHelpingTutors, a new tutor teaching Year 11 biology spent about two hours on a Google Slides deck and taught the whole lesson in 35 minutes. The replies are practical. One says to plan one main activity and do any longer explanation on a whiteboard: draw pictures, make a mind map, and keep the student involved, with no more than about a fifth of the session spent talking. A science teacher says they teach from a rough plan, interactive resources and a bank of questions, using a whiteboard. Another says to build a bank of diagrams once and reuse it, and another suggests having the student draw a diagram and explain it in their own words. Those habits turn into four jobs for the board:

• Draw the diagram. A cell, a membrane, a pathway, drawn live so the student sees the order.
• Write the reasoning next to it, one short line at a time.
• Let the student draw the next case in their own colour and explain it.
• Keep a reusable page. Leave the board open as the revision sheet, and copy it for the next student.

A tablet or pen tablet makes diagrams faster than a mouse; see which pen tablet to buy and online tutoring setup. For a concept-map version of biology notes, see the biology concept map.

An osmosis lesson in five steps

OpenStax Biology 2e, section 5.2, defines tonicity as how an extracellular solution can change a cell's volume by affecting osmosis. In a hypotonic situation the extracellular fluid has a lower osmolarity than the cytoplasm and water enters the cell; in a hypertonic one the outside has a higher osmolarity and water leaves. The board above follows that order with our own made-up percentages:

1. 1Ask for a sketch first: before explaining, ask your student to draw a cell in salty water and say what they expect.
2. 2Draw the case: a cell in a beaker, 0.9% salt inside, 0.1% salt outside.
3. 3Name the outside: less salt outside than inside, so the outside fluid is hypotonic. The prefix describes the outside fluid, not the cell.
4. 4Draw the water arrows: water moves in and the cell swells. Only water crosses; the salt cannot.
5. 5Student's turn: 3% salt outside. Your student draws the arrows out of the cell and writes the reasoning in blue.

The common slip is saying salt moves in. The red notes on the board name the two usual ones: hypo and hyper describe the outside fluid, and the solute cannot cross, so water moves.

Drawing biology on Instaboard

On Instaboard you draw diagrams with the pen, like a whiteboard in a room. Here is what that means, so you can decide before the lesson:

• Hand-drawn diagrams. Cells, membranes, arrows and pathways are pen drawings. The cell and arrows on the board above are drawn stroke by stroke.
• Hand-written labels. Names and reasoning are written, not typed. Cards and lists hold typed notes if you want a tidy checklist beside the drawing.
• The worksheet. Import the student's PDF and write on it. Each imported PDF uses one of the 5 free boards.
• A textbook figure. You can add an image to a card, but a free board holds 3 images, and drawing the figure with the student is usually the point.

When screen share or another tool is the better choice

• You need to show a real figure or an animation. Share your screen and use the board for the working, since Instaboard has no figure library or animation.
• Your platform already has a whiteboard you like. A tutor replying in a May 2026 thread on r/Preply says Preply's built-in whiteboard is poor for drawing diagrams and uses a separate whiteboard instead. If your platform's own whiteboard works for you, keep it.
• You want a recording of the lesson. Instaboard does not record.
• You teach a large class. Instaboard has no class mode.

Instaboard fits when you teach by drawing, you want the student to draw the next case, and you want the call, the diagram and the reasoning on one link.

Use the lesson board in five steps

1. 1Open the biology board above and make it yours.
2. 2Send your student the link, or press Call on the board so the lesson runs in one place. They sign in free once to write.
3. 3Swap in your topic. Replace the cell with the diagram you are teaching, such as a membrane, a pathway or a cycle.
4. 4Let the student draw the next case in their own colour and explain it out loud.
5. 5Leave the board open as the revision sheet and start the next lesson from it.

The same pattern works for other subjects: how to teach chemistry online and how to teach math online. For free video lessons on the same topics, see the Boardling biology lessons.

What Instaboard doesn't do for biology

• No diagram library, no animation, no 3D. Diagrams are hand-drawn ink.
• No handwriting reading. Handwritten labels are not searchable.
• Whole-stroke eraser only. You cannot rub out part of a line; erase the stroke and redraw it.
• No recording of the lesson, no class mode, no scheduling.
• Students sign in to write. Anyone with the link can view; writing needs a free sign-in. Free calls run 60 minutes.
• Free covers 5 boards. Each imported PDF uses one of them. Pen strokes do not count toward the 150-item limit; cards and lists do.
• Free boards are shared by link, so use first names only.

Questions