A free printable microscope and cell theory worksheet for Grade 8 science.
By Kris Reddy, Ontario teacher · Updated October 17, 2026 · 37 questions (30 marks) · PDF + answer key
This free parts of a microscope worksheet combines the compound light microscope with cell theory for Grade 8 science. Students label 12 parts of a detailed microscope diagram, match parts to their jobs, calculate total magnification, and put the steps for focusing a slide in the right order.
The second page covers field of view and estimating the size of a cell, why the letter "e" looks upside down and backwards, the three parts of the cell theory, the scientists who built it (Hooke, van Leeuwenhoek, Schwann and Virchow), and a microscope-safety mistake. Every calculation was checked by computer. To print it, use the Download button above.
| Part | Skill practised | Marks |
|---|---|---|
| A | Label 12 parts of a compound light microscope | 6 |
| B | Total magnification | 3 |
| C | What does each part do? | 3 |
| D | Order the steps for focusing | 3 |
| E | Field of view and cell size | 6 |
| F | What you see (inverted image) | 2 |
| G | The cell theory | 3 |
| H | Who discovered what? | 2 |
| I | Spot the mistake | 2 |
The parts of a microscope worksheet supports the Ontario Grade 8 science curriculum, Life Systems: Cells, where students learn the cell theory and use a microscope to observe cells safely. It pairs well with the cell organelles worksheet and the plant and animal cell worksheet.
A compound light microscope uses two sets of lenses, the eyepiece and an objective lens, to magnify a specimen. Light from below passes up through a thin slide, through the lenses, and into your eye. Here is the diagram students label in Part A of the parts of a microscope worksheet:
| Part | What it does |
|---|---|
| Eyepiece (ocular) | The lens you look through; usually 10× |
| Body tube | Holds the eyepiece at the right distance from the objectives |
| Revolving nosepiece | Rotates to switch between objective lenses |
| Objective lenses | Main magnifying lenses, usually 4×, 10× and 40× |
| Stage and stage clips | Flat platform that holds the slide; clips keep it in place |
| Diaphragm | Controls how much light reaches the specimen |
| Light source | Shines light up through the specimen |
| Coarse adjustment knob | Large focusing movements, on low power only |
| Fine adjustment knob | Small, sharp focusing; the only knob to use on high power |
| Arm and base | Hold up the microscope; carry it by the arm with a hand under the base |
Part C of the parts of a microscope worksheet checks these jobs. Always carry a microscope with two hands: one on the arm and one under the base. For more background, see optical microscope on Wikipedia.
To find the total magnification, multiply the eyepiece by the objective lens: 10× × 40× = 400×. The field of view is the diameter of the bright circle you see. As magnification goes up, the field of view gets smaller, by the same factor:
| Eyepiece | Objective | Total magnification | Field of view |
|---|---|---|---|
| 10× | 4× | 40× | 4.5 mm |
| 10× | 10× | 100× | 1.8 mm |
| 10× | 40× | 400× | 0.45 mm |
Field of view lets you estimate cell size. If 6 onion cells fit across a 1.8 mm field at 100×, one cell is about 1.8 ÷ 6 = 0.3 mm, or 300 µm (micrometres). Part E of the parts of a microscope worksheet walks through these steps. Very small sizes like these are often written in scientific notation; see the scientific notation worksheet.
The lenses in a compound microscope invert the image. A letter e on a slide looks upside down and backwards, as if it had been turned 180° (option D below). It also means that if you move the slide to the left, the image moves to the right. Part F of the parts of a microscope worksheet tests both ideas.
Microscopes made the cell theory possible. It has three parts:
It took almost 200 years and several scientists to piece this together:
| Year | Scientist | Contribution |
|---|---|---|
| 1665 | Robert Hooke | Looked at cork and named the tiny boxes "cells" |
| 1670s | Antonie van Leeuwenhoek | First to see living microorganisms |
| 1838 | Matthias Schleiden | All plants are made of cells |
| 1839 | Theodor Schwann | All animals are made of cells |
| 1855 | Rudolf Virchow | All cells come from other cells |
Part H of the parts of a microscope worksheet asks students to match four of these scientists to their discoveries. Read more about the cell theory on Wikipedia.
These questions match the parts of a microscope worksheet PDF, which has the full microscope diagram and the letter-e options drawn.
Label 12 parts (questions 1–12) using the word bank.
Open each part to check the parts of a microscope worksheet answers. The printable key, with the labelled diagram, is on the last two pages of the PDF.
These come up often in class and when marking this parts of a microscope worksheet.
For more practice, try the scientific method quiz and the biological kingdoms quiz.
Yes. The worksheet and its answer key are free to download and print as one PDF, with no account needed.
The eyepiece, body tube, revolving nosepiece, objective lenses, stage, stage clips, diaphragm, light source, coarse and fine adjustment knobs, arm and base.
Multiply the eyepiece magnification by the objective lens magnification. A 10× eyepiece with a 40× objective gives 10 × 40 = 400×.
All living things are made of one or more cells; the cell is the basic unit of structure and function in living things; and all cells come from pre-existing cells.
The lenses of a compound microscope invert the image, so it appears upside down and backwards. Moving the slide left makes the image move right.
Ready to start? Use the Download button above to print the free parts of a microscope worksheet double-sided, and keep the answer key pages for marking.