Science Learning intention To know how microscopes have advanced over time and to be able to compare the advantages and disadvantages of the different types of microscopes You will need A pen and paper ID: 1046893
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1. Year 8Lesson 8 – cellsScience
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3. Learning intentionTo know how microscopes have advanced over time and to be able to compare the advantages and disadvantages of the different types of microscopes.
4. You will need• A pen and paper.• A digital device.
5. Lesson 7: challenge answerA virus can be viewed under a scanning electron microscope or a transmission electron microscope.Source: An illustration of the hepatitis C virus. Credit: U.S. Centers for Disease Control and Prevention
6. Microscopy articleRead the microscopy article.Return to the PowerPoint after you have finished reading the article.
7. Microscope magnification comparisonsUse the interactive lesson on microscopes to compare microscope magnification.Return to the PowerPoint on the completion of the online lesson.
8. QuestionsUse the resources on slide 6 (microscopy article) and slide 7 (interactive lesson on microscopes) to answer the following questions:What is the name of a photograph taken using a microscope?What is the difference between magnification and resolution?How are electron microscopes able to obtain images with such high magnification?Are there any disadvantages that electron microscopes have?What is the main difference between SEM and TEM?
9. Microscope comparisonmicroscopemaximum magnificationadvantagesdisadvantagesDraw and complete the table below using the resources from slide 6 (microscopy article) and slide 7 (interactive lesson on microscopes).
10. ReviewA photograph taken using a microscope is called a micrograph.2. Magnification is how much bigger a sample appears to be under the microscope. Resolution is the ability to distinguish between 2 points on an image, the amount of detail. An increase in magnification does not increase the resolution of the image.Watch the ‘Objects Under An Electron Microscope!’ video to see objects under an electron microscope.Return to the PowerPoint when it is finished.Source: Objects Under An Electron Microscope! on YouTube (Mr Scientific, 2020)For your safety, watch this video in the slideshow without accessing YouTube.
11. ReviewAn electron microscope uses an ‘electron beam’ to produce the image of the object and magnification is obtained by ‘electromagnetic fields’.Unlike light microscopes, in which ‘light waves’ are used to produce the image and magnification is obtained by a system of ‘optical lenses’. Therefore it can see images as small as 0.2 nanometres.4. Electron microscopes are quite large and very expensive. They cannot observe living cells or organisms.
12. ReviewThe main difference between scanning electron microscope (SEM) and transmission electron microscope (TEM) is that SEM creates an image by detecting reflected or knocked-off electrons, while TEM uses transmitted electrons (electrons that are passing through the sample) to create an image. As a result, TEM offers valuable information on the inner structure of the sample, while SEM provides information on the sample’s surface and its composition.
13. ChallengeWhat is a unicellular or single celled organism?
14. Key termsSEM: scanning electron microscope is used to observe microscopic information about the surface or near-surface region of a specimen. SEM is used in a variety of industries, such as materials science, forensics, industrial manufacturing, and life sciences. TEM: transmission electron microscope is a high-resolution imaging technique in which a beam of electrons passes through a thin sample to produce an image.
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