Introduction to the Microscope Types Care Parts Using Nosepiece Students will have their microscopes out, for reference as we go through each of the steps. As an introduction, students will be asked what kinds of things they can do with this tool.

Types of Microscopes First microscopes were simple scopes One magnifying lens (i.e. one magnifying glass) Compound Microscopes Two magnifying lenses & a source of light Dissection Microscopes Low magnification (cannot see cells) Used for dissection to get a better look at the larger specimen Scanning electron microscope (SEM) Extremely detailed 3D views of the surface of the specimen (think of “S” for surface) Specimens are coated with metal Transmission electron microscope (TEM) Electrons pass through the specimen - can view internal structure (think of “T” for through) Specimen must be sliced into an extremely thin section - 20-100 nm and stained with metals

SEM images Bacteria Termite Blood cell Ballpoint pen

TEM images Mitochondrion Bacterium Rough ER Chloroplast

Microscope Care Always carry with 2 hands Never allow cords to hang over the counter Do not force knobs Always use the fine focus if on any power higher than scanning (4X) Loosely wrap the cord around the scope for storage Never place on top of the vent in front of your station! Teacher demonstrates how to hold the microscope, where the lens paper is located and how to use it. Students will be invited to turn the knobs and observe the stage as it moves up and down. Teacher will demonstrate how to store the microscope.

Microscope Parts Ocular Lens- Eyepiece Revolving Nosepiece Arm Objective Lens Stage Stage Clips This is the exact version of the microscope used in class. Students will be identifying the parts on the microscopes at their desks as we go along and what their functions are. Coarse Adjustment Focus Diaphragm Fine Adjustment Focus Light Source Base

Parts of the Microscope Slide Coverslip Slide

Using the Microscope Turn the microscope on Lower stage Click Nosepiece to the shortest setting (4X) Place the Slide on the Microscope Use Stage Clips Look into the Eyepiece Use the Coarse Focus to slowly bring specimen into focus Bring specimen into focus using Fine Focus knob Adjust diaphragm if necessary Give students a slide from the “common things” set, each student will practice focusing and changing objectives.

Using High Power Follow steps to focus using low power Carefully turn the nosepiece to the next longest objective Do NOT use the Coarse Focusing Knob Use the Fine Focus Knob to bring the specimen into focus Have students exchange slides so they can look at different things, walk them through using the high power objective to focus slides. Emphasize not using the coarse objective during this process, as it will crack the slides.

When Finished Observing Bring stage all the way down Turn nosepiece so that smallest objective is directly over the slide Carefully remove the slide!

Microscope Terms Magnification Resolution Field of View Depth of Focus Image Inversion

Magnification Making an image appear larger than its actual size For example: magnification value of 100X means an image appears 100 times larger than its actual size Total Magnification = objective mag. x ocular mag. Example: 40X mag. (objective) times 10X mag. (ocular) = total of 400X mag.

Resolution The ability of a microscope to show the details of an object, ability to distinguish between 2 lines The higher the resolution the clearer the image Both high magnification and good resolution are needed to view the details of extremely small objects clearly.

Focusing on an Object Remember: Locate and Focus on your object with the scanning (smallest) objective lens first This provides: Greater Depth of Focus – depth of 3D objects (layers) Greater Field of View – how much of the image you can see