1 Lab 1: The Microscope

General Information

Lab 1 helps students become familiar with the compound light microscope and its use. Students are guided through a series of exercises showing them:

  • What parts make up a microscope.
  • How to set a comfortable ocular width.
  • How to put a slide on the stage.
  • How to navigate around a slide.
  • How to move from scanning power to low power to high power.

Students will also learn how to make a wet mount slide and explore the inverse relationship between magnification and field of view/depth of field.

NOTE — This lab does not teach students how to use the oil immersion lens.

Purchasing Information

Required materials for Lab 1 include:
  • A class set of compound microscopes — preferably with 4x, 10x, and 40x objective lenses
  • A class set of the following slides and slide materials:
    • Coloured threads slides
      • Available from many places, including Amazon, Ward’s Science, and Boreal Science
    • Blank slides
      • 1 class set is recommended in case of breakage
      • Available from lots of places
      • Do not buy plastic ones, as they scratch and bend easily
    • Coverslips
      • Buy lots as they are disposable, and each student needs 2 per lab.
      • Do not buy plastic ones as they scratch and bend easily.
    • A set of random slides with neat samples on them
      • E.g., slides with 4 items per slide that are themed: textiles, insect parts, tiny plants, animals, etc.
      • Some sets are available on the following website: Prepared Slides Bundle: Set I & II (Learning Resources, n.d.).
  • Small scissors (like sewing or kids scissors) — 1 pair for every 4 students
  • Forceps (or tweezers) — 1 pair for every 4 students
  • Small glass bottles with droppers — 1 for water and 1 for IKI
    • Brown glass works best for IKI due to its photosensitivity (see Additional Notes for more information).
  • Cutting boards with small paring knives – 1 for every 8 students
  • Clear plastic rulers — 1 for every 4 students
  • Printed lab labels — laminating them is optional
  • Newsprint with small font
  • (On lab day) Onion — 1 medium-sized onion is enough for a lab with 20 students, where each makes their own slide.

Lab Setup

Preparations

  • Buy an onion.

Lab Activity Setup

Time: Approx. 1 hour

Board Notes

Welcome to Lab 1: Safety and the Microscope
  • Please hand in:
    • Signed safety contract from page 7 of your lab manual
    • Pre-Lab 1 Assignment from page 11 of your lab manual
  • Find a partner to work with (you each get your own microscope)
  • If you get stuck, first ask your partner, then ask the teacher
  • Remember to call your teacher over when you reach a symbol
  • Cleanup:
    • Slides – get cleaned and returned
    • Coverslips – go into the sharps disposal container
    • Microscopes back where you got them
    • Wipe down your lab bench and wash your hands before you leave

Setup Photos

Figure 1.1: Lab 1 Activity 1 Setup (Credit: Christine Miller) CC BY-NC-SA 4.0 license
Figure 2.1: Lab 1 Activity 2 Setup (Credit: Christine Miller) CC BY-NC-SA 4.0 license
Figure 3.1: Lab 1 Activity 3 Setup (Credit: Christine Miller) CC BY-NC-SA 4.0 license

Bin Lab

Figure 4.1: Lab 1 Bin (Open) (Credit: Christine Miller) CC BY-NC-SA 4.0 license
Figure 5.1: Lab 1 Bin (Closed) (Credit: Christine Miller) CC BY-NC-SA 4.0 license

Troubleshooting Microscopes

Why can I not see anything?

Check that:

  • The microscope is plugged in and turned on.
  • The slide is in the field of view.
  • The objective lens is clicked into place.
  • The iris diaphragm is set properly.
  • The blue filter is working properly.
  • Only one eye is used to view (like a pirate).
  • The depth of field is not decreased to the point that the item cannot be focused on.

Why do I lose my image when I move up in magnification?

Check that:
  • The image is centered in the field of view and very well-focused before increasing magnification.
  • The objective lens is in properly and clean.
  • The iris diaphragm is set properly.

Why will my course focus not work / why does my microscope keep going out of focus?

Focus tension:

  • Cannot move the course focus – the tension is too tight.
  • The microscope falls out of focus spontaneously – the tension is too loose.

Additional Notes

IKI is photosensitive and can degrade if exposed to too much light. Degradation causes the colour to change, like in the Figure 1.6 below.
Two bottles of IKI. One is a clear yellow colour where the IKI has degraded and can no longer be used as an indicator. The other bottle is a dark amber colour where the IKI is still useable as an indicator.
Figure 1.6: Degraded vs. Good to Use IKI (Credit: Christine Miller) CC BY-NC-SA 4.0 license

Media Attributions

References

Learning Resources. (n.d.). Prepared slides bundle: Set i & ii. https://www.learningresources.com/item-prepared-slides-bundle-set-i-ii.

License

Icon for the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License

Provincial Level Biology Lab Manual: Instructors Guide Copyright © by Christine Miller, TRU Open Press is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License, except where otherwise noted.

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