Teacher Portal:
Microscopic Explorations
Investigation 1 – PostLab
ASK WHY
Microscopes are one of the most important scientific instruments developed. In fact, in the medical field, microscopes are largely responsible for making modern medicine “modern”!
BRANCH OUT
You might wonder which came first, the microscope or the telescope. Actually, they appear to have appeared at about the same time although it is thought that the microscope may have come first. In either case, the first forms of both instruments were developed in the 16th century (the n1500s). It isn’t that much of a stretch to imagine that, once the microscope was invented, that someone would consider making similar instruments that could make distant objects appear closer.
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SLIDE MICRO1-post-1
In this PostLab session, we will go over the experiences and results from the Lab for Investigation 1.
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SLIDE MICRO1-post-2
What was the theme or “focus” of Investigation 1? The focus of the investigation was to examine how images of objects may appear when viewed with different types of lenses. Students investigated the appearance of an oat cereal piece with the unassisted eye, a convex lens, and a concave lens. Students also investigated the appearance of the word “Letter” on the Letter “e” slide with the unassisted eye, the convex lens, the concave lens, and the 4X objective of the microscope.
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SLIDE MICRO1-post-3
What questions were asked during Trial 1? How did you answer these questions? Students investigated the questions: How are the images produced by lenses different than the object viewed with the unassisted eye? How are they similar? How are the images produced by concave and convex lenses different? How are they similar? To answer these questions, students viewed a piece of oat cereal under three different conditions: with the unassisted eye, with a convex lens, and with a concave lens.
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SLIDE MICRO1-post-4
Describe the appearance of the oat cereal piece when viewed with the unassisted eye. Describe the appearance of the oat cereal piece when viewed with the convex and concave lenses. (Use the sketches you drew in your Scientist Data Record to help you) Student answers will vary. However, students’ answers should include a description of the oat cereal under each viewing condition. In addition, students should indicate that the oat cereal appeared larger and more detail could be seen when it was viewed with the convex lens. It appeared smaller and less detail could be seen when it was viewed with the concave lens. For example, the oat cereal piece was round, beige-colored with a hole in the middle, and textured with small bumps on it. When viewed with the convex lens, it appeared larger than with the unassisted eye. The bumps seen with the unassisted eye now appeared to be small holes and the holes were a different color from the rest of the cereal piece. When viewed with the concave lens, the cereal piece appeared smaller than with the unassisted eye. In contrast to its appearance with the unassisted eye and convex lens, its surface looked smooth.
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SLIDE MICRO1-post-5
Think about the passage you read at the beginning (PreLab) of the investigation and the terms object and image. Did you observe any objects in your investigation? Did you observe any images? Students should indicate that the oat cereal piece and the Letter “e” slide were objects. Examples of images students observed during the Investigation included the appearance of the oat cereal and the word “letter” seen when using the concave and convex lenses.
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SLIDE MICRO1-post-6
What questions were Trial 2 designed to answer? How did you answer these questions? Trial 2 was designed to answer: How are the images produced by convex and concave lenses and a microscope different? Similar? How are the images produced by a microscope similar to that of the unassisted eye? Different? To answer these questions, they viewed the Letter “e” slide with the unassisted eye, the convex lens, the concave lens, and the 4X objective of the microscope. For each condition, students sketched the appearance of the word “Letter.” When viewing the slide with the unassisted eye, the convex lens, and the concave lens, students also measured the height and width of the word “Letter.”
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SLIDE MICRO1-post-7
Describe the appearance of the word “Letter” when viewed with the unassisted eye. Describe the appearance of the word “Letter” when viewed with the convex and concave lenses. (Use the sketches you drew in your SDR to help you) Student answers will vary. However, students’ answers should include a description of the word “Letter” under each viewing condition. In addition, students should indicate that the word “Letter” appeared larger and more detail could be seen when it was viewed with the convex lens and it appeared smaller when it was viewed with the concave lens.
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SLIDE MICRO1-post-8
Quick Steps for Using the LabLearner Elementary Compound Microscope
□ Turn on the light (8) by turning on the light source.
□ Turn the nosepiece (3) until the low or 4X power objective (4) is in position for viewing. The low power objective is that is marked with the red stripe.
□ Place the slide on the stage (5) under the stage clips so that the word “Letter” on the label is under the objective (6)
□ Look into the eyepiece (1).
□ Rotate the aperture control (7) to the largest opening to allow the most light to go through the stage. Do not use the colored filters.
□ Rotate the focus control knob (9) to move the stage (5) towards or away from the objective. (4)
□ Rotate the focus control knob until the letter “e” in the word “Letter” is in focus and can be seen clearly.
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SLIDE MICRO1-post-9
This slide presents images of the word “Letter” and the letter “e” when viewed with the unaided eye, convex and concave lenses, and the compound microscope. Discuss the differences in the images produced by each of these methods of observation.
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SLIDE MICRO1-post-10
Divide students into the five cooperative groups that they were assigned in the lab. Encourage student groups to develop a table that will organize the quantitative data they collected in the lab. Students should construct their table in problem 5a of their SDRs. Remind students that the Creation and Completion of a Data Table is a tool from the Procedural Toolbox.
If necessary, assist students in this process by reviewing the steps they should consider as they create and complete a data table that organizes their results. The following are guiding questions that students should ask themselves as they create and complete a data table.
KEYS
