Using Microscopes Grade Level: 6, 7, 8, 9, 10 Duration: 30-45 minutes Classification: Classroom Subject(s): Biology, Microbiology Categories (STEM): Science, Technology Keywords: Staining, Microscopes, Microbes Introduction

● Summary: Students will learn how to properly use microscopes and view different cells and organisms.

● Description: Microscopes are often used to view different types of organisms, cells, and organelles. Microscopes can be used to visualize changes in cell structure and identify unknown organisms. Students will learn all the parts of microscopes and how to use and adjust them. Another important step of using microscopes is to learn how to properly prepare slides and wet mounts. Different organisms, cells, and organelles will be viewed under a microscope. In case of school policy limitations, note that student role models are required to cut vegetables at schools before the visit starts. *Note - School is responsible for providing microscopes for this activity. Online Resources: https://www.youtube.com/watch?v=SUo2fHZaZCU\

Vocabulary  Organisms: an individual animal, plant, or single-celled life form  Cell: smallest structural unit of an organism  Organelle: organized structures (compartments) within a living cell  Nucleus: dense organelle (generally in the middle of a cell) that contains genetic information  Wet Mount: microscope slide holding a specimen suspended in a drop of liquid

Materials Materials Quantity Reusable? Nail Polish 1 red per classroom Yes Microscopes (provided by school) TBD by school Yes Dirty Pond Water (a lot of algae or other 3 jars/small containers per No organisms) classroom Cover Slips 1 box per classroom (20 slips) Yes Microscope Slides 1 box per classroom (20 slides) Yes Green Pepper, Red Pepper, Red Onion 1 quarter-sized chunk of each No Fresh Leaves 2 per classroom No Scalpel or Razor Blade 2 per classroom Yes Microscope Parts Handout 2 total Yes Droppers 1 per 3 students Yes Paper Towels 1 roll No Slide Images Handout 1 per 2 students Yes Nail Polish Remover 1 bottle per classroom Yes

Directions

● Before the activity starts, cut vegetable chunks and leaves into small slices - razor thin, toothpick wide ● Give students overview of microscopes and activity using the vocabulary words. ● Have students pair up at each microscope. If there are not enough microscopes for every pair have students form bigger groups. Place a Slide Images Handout at each microscope. ● Have students practice preparing slides at each station by making a wet mount. Microscope Parts Handouts can be used for role models and students to reference. Explain the 2 drop method (see image below) and the importance of making sure there are no bubbles. ● Nail polish can be used instead of water for vegetable/leaf slides, if there is an experienced Role Model that has been successful, show a test run. Make sure acetone can remove nail polish from slides and coverslips before using. Use paper towels to blotch excess water or nail polish.

● Vegetable & Leaf Slides: Add a drop of water, put vegetable/leaf slice on slide, add another drop of water on top, and add cover slip at diagonal angle to seal air tight, without bubbles. If the vegetable/leaf slice is not thin enough, the cover slip will not seal air tight on both slides. ● Pond Water Slides: Add a few drops of dirty pond water onto a slide. Add a cover slip at a diagonal angle and seal air tight on both sides. ● Before viewing the slides, go through the Microscope Parts Handout and how to adjust all of them. Make sure students know they must change their magnification in the order: low → medium → high. Make sure students don’t accidentally break slides or cover slips by using high magnification with their stage too high up. Have students secure slides with stage clips to prevent slide breakage. ● Point out different organisms, cells, and organelles and their varying shapes on different prepared slides. ● All handouts can be collected and reused. ● When cleaning up, wash all slides with water. If nail polish has been used, use acetone to clean off the slides. All plant and vegetable material can be thrown. Pond water should not be put down the sink and thrown outside if possible. TROUBLESHOOTING ● If you have difficulty helping students view things under a microscope, start with fixing the coarse adjustment and fine adjustment and work up to the higher powered lenses. Focus the microscope slide for each objective lens at each magnification before adjusting to a higher magnification objective lens. Only use coarse adjustment on the low magnification setting.

Activity Extension ● Have students learn how to make a blood smear slide with water instead of blood. Put a couple drops of water onto the center of a microscope slide. Use a second slide (not cover slip) and touch the second slide to the water and push upward towards one end of the slide. When you get close to the edge of the slide drag the slide backward so that the “blood” (water) reaches the other side of the slide. ● Have students go around and view other’s microscope slides. ● Go through all vegetable types and make different pond water slides.

Discussion Questions

● What organisms, cells, and organelles did you see? nucleus ● Did they vary in shape? If so, what? ● What is the order for increasing magnification on a microscope using objective lenses? ● What is staining? How is it used to prepare microscope slides? ● Did you observe any moving organisms in the pond water? What unique feature allows organisms to swim? Flagella

What is happening?

● Students will learn to prepare their own slides, identify and adjust parts of a microscope, and view different organisms under a microscope.

Applications: ● Majors ● Biology, Microbiology, Entomology (study of insects) ● Jobs ● Any scientific research can use microscopes ● Scientist, Data analytics ● Physicians, Medical Laboratory Scientist ● Forensic Laboratory Technicians (threads, fibers, metals, trace analysis) ● Hobbies ● Bug identification ● Real world applications ● CDC and WHO ● Forensic Scientist & Criminal Court Evidence ● Research Papers

This activity was last updated in fall 2020 by Student Role Models.