Magnification Calculations and Graticules | BTEC Applied Science Unit 1

A free, complete sample lesson for Unit 1 (Principles and Applications of Science I), biology section: magnification, units, scale bars and eyepiece graticules.

Learning objectives:

• Use I = A × M to calculate magnification, image size or actual size.
• Convert between mm, µm and nm.
• Use a scale bar to find actual size.
• Calibrate an eyepiece graticule with a stage micrometer.

What’s included:

• Student worksheet (PDF and editable Word)
• Teacher version with model answers and mark schemes (PDF and editable Word)
• Teacher notes: lesson flow, common misconceptions and practical/safety notes
• Retrieval starter (5 marks)
• Structured tasks with key-idea boxes and clear diagrams
• Check for Understanding quiz (10 marks) with a confidence self-assessment
• Exam-style practice (15 marks), ending with a levels-marked 6-mark question with indicative content

Specification coverage:

• B1 · Microscopy: calculating magnification and actual size using I = A × M, with unit conversions.
• B1 · Microscopy: scale bars and calibrating an eyepiece graticule.

About 60 minutes of teaching; the exam-style section works in class or as homework. All questions are original.
Note: some questions ask students to measure from the page, so print at 100% scale (not “fit to page”).

Written for the Pearson BTEC Level 3 Nationals in Applied Science. Not endorsed by Pearson. Free to use under the Creative Commons NoDerivatives licence.

Like this lesson? The full Unit 1 course and chemistry, biology and physics bundles are available in the Delocalised Science shop.