Classifying and observing microorganisms

This topic provides the fundamental introduction to microorganisms and supports subsequent topics that focus on cell biology and microbiology. Students need to develop an understanding of the basic structure of microorganisms, including those with cellular and non-cellular features. An understanding of scale and units of measurement is also required to appreciate the significant differences in size between cells and viruses or prions.

Once students have an understanding of scale, they need to understand the relative benefits and drawbacks of light microscopes and transmission & scanning electron microscopes. As that latter two types of microscope will not usually be encountered in school or college science, this creates a challenge for students being able to visualise and understand the principles behind their use.

Staining techniques and reagents such as Gram staining, Giemsa staining, haematoxylin and eosin are used to classify different types of microorganism and diagnose disease. Students need to develop an understanding of what these techniques involve and their practical application.

Whilst this list provides a source of information and ideas for experimental work, it is important to note that recommendations can date very quickly. Do NOT follow suggestions which conflict with current advice from CLEAPSS, SSERC or other recent safety guides. eLibrary users are responsible for ensuring that any activity, including practical work, which they carry out is consistent with current regulations related to Health and Safety and that they carry an appropriate risk assessment. Further information is provided in our Health and Safety guidance.

Produced by Wellcome, this card game allows students to compare and contrast four major types of cells (plant, animal, fungal and bacterial). They could be used in lessons to consolidate learning or independently for revision. Various activities could be possible using the cards including individual sorting tasks followed by pair and share discussions with peers, games involving recall of structural details, etc

From the Centers for Disease Control and Prevention, this website provides an overview of the three main classes of parasites that can cause disease in humans: protozoa, helminths and ectoparasites. Each category has specific examples which can be explored in more detail with profile pages on diagnosis and detection, sources of infection, illness and symptoms, prevention and control providing comprehensive information and images. The website could be used as a research source for students and they could be tasked with providing a summary of a presentation on a named parasite.

This is a short video produced by the National STEM Learning Centre on how to set up and focus a light microscope. It is not uncommon to find that Level 3 students have had variable practical experience in school and so some students may not be aware of basic techniques for observation of specimens. The video provides concise instruction and is suitable for a range of age groups, including post 16.

This practical is focused on developing microscopy skills, which can often be underdeveloped in level 3/KS5 students. The practical allows students to discuss the concepts of size in relation to magnification and resolution in relation to the different organisms they can see.

The hanging drop technique is a well-established method for examining living, unstained, very small organisms. The traditional procedure involves a glass slide with a central circular concavity into which a drop of fluid ‘hangs’ from a coverslip. Cavity slides are relatively expensive, and coverslips are very fragile. The apparatus described in this procedure is cheaper, more robust and less fiddly to work with.

Quality AssuredCategory:SciencePublisher:Oxford Sparks

An activity that allows students to practice carrying out magnification calculations and learn the difference between magnification and resolution. This is often an area that causes some conceptual difficulty with students and is best taught by means of a practical activity where students can see the difference for themselves. The activity involves six different workstation activities that students can rotate round in the course of a one hour lesson. Answers to each of the activities are provided.

Quality AssuredCategory:SciencePublisher:Gatsby Science Enhancement Programme

This resource is an article from the Catalyst magazine which looks at the work of the early microscopists, including Leeuwenhoek, Hooke and Swammerdam. This could be used as a ‘read ahead’ task for students to complete prior to the lesson, a comprehension task with the addition of some simple questions relating to the article or students could be asked to provide a written or verbal summary of the key points.

Their work looked at the miniature world beyond human sight and through publications raised awareness of phenomena such as how insects functioned and how disease spread. The article also examines the use of simple and compound microscopes

Quality AssuredCategory:SciencePublisher:Microbiology Society

Useful to both teachers and technicians, this manual provides a basic introduction to microbiology, aseptic technique and safety. The manual is arranged in two sections, the first dealing with good microbiological laboratory practice, the second providing practical investigations that can be carried out. Clear photographs and methods are provided and these could form the basis of instructional sheets that are used by students in the laboratory. A protocol for Gram staining is included.

Quality AssuredCategory:SciencePublisher:Catalyst

An article from the Catalyst magazine, this resource explores how the development of the electron microscope has allowed greater detail of cellular structure and organelles to be understood. Detailed electron micrographs are included and this would serve as a good introduction or pre-reading task to the topic of electron microscopy and/or cell organelles.

This resource is an online simulation of a scanning electron microscope (SEM). Students can use the simulation to view various samples including everyday objects, forensic materials, hydrophobic surfaces and arthropods. They can also adjust the accelerating voltage, spot size and height distance as they would if operating the device for real. This would be a good activity for students to complete as a homework task or as part of a blended remote lesson and allows them to experience the use of an SEM rather than simply learning about the theoretical details. It could be supplemented by some questions or tasks to complete that have been previously prepared by the teacher, in order to give a focus to the activity.

From the Genetic Science Learning Centre, this is a zoomable animation which illustrates the relative size of objects as it zooms in from metres to picometres. This is a good animation for students to view in order to gain some appreciation of why different units of measurement are necessary and the huge differences in size between objects and structures that are microscopic. The animation could be linked to a virtual learning environment platform for students to access independently or could be incorporated into a lesson.

This resource provides an online simulation for calibrating an eyepiece graticule. The use of an eyepiece graticule and stage micrometer can often be problematic for students, as they require an understanding of scales and units of measurement in order to calibrate the graticule successfully. The animation could be used as an additional means of practicing this skill and understanding the key principles. It would perhaps be best supplemented through the use of a teacher-designed worksheet with tasks and questions that give the students some direction.

From the London School of Hygiene and Tropical Medicine, this video demonstrates how to stain patient tissue samples with the Giemsa solution and detect the presence of Leishmania under the microscope. The video includes details of the Giemsa staining procedure followed by the techniques used to diagnose Leishmaniosis using the light microscope. A transcript of the video can be downloaded and this could be converted into an active video worksheet with questions and tasks for students to complete while the video is viewed.

A long read article from Leica Biosystems, this provides a detailed step by step guide to the procedure, background information about the uses and application of the staining technique, advice on troubleshooting H and E stains and tips to ensure better staining. The article would be of use to teachers who are preparing to teach this technique and are unfamiliar with the procedure.

From the Centers for Disease Control and Prevention, this weblink provides a concise but detailed summary of all aspects of this bacterial species and its role in human disease. Students could be tasked with using this website as a source of information for research and presentations, as a source to answer directed questions posed by the teacher in a worksheet task or excerpts could be used by teachers to guide lesson planning.

From the Centers for Disease Control and Prevention, this weblink provides a concise but detailed summary of all aspects of the HIV virus and its role in human disease. Students could be tasked with using this website as a source of information for research and presentations, as a source to answer directed questions posed by the teacher in a worksheet task or excerpts could be used by teachers to guide lesson planning. The website also provides information sheets and a timeline that looks at the history of HIV.

From the Centers for Disease Control and Prevention, this weblink provides a concise but detailed summary of all aspects of the parasitical protist that causes malaria. Students could be tasked with using this website as a source of information for research and presentations, as a source to answer directed questions posed by the teacher in a worksheet task or excerpts could be used by teachers to guide lesson planning. The webpage includes a biology section which explores the life cycle of the parasite.

From the Centers for Disease Control and Prevention, this weblink provides a concise but detailed summary of all aspects of the prion that causes CJD. Students could be tasked with using this website as a source of information for research and presentations, as a source to answer directed questions posed by the teacher in a worksheet task or excerpts could be used by teachers to guide lesson planning.

From the Centers for Disease Control and Prevention, this weblink provides a concise but detailed summary of all aspects of the fungus Candida auris which is emerging as a serious global health threat. Students could be tasked with using this website as a source of information for research and presentations, as a source to answer directed questions posed by the teacher in a worksheet task or excerpts could be used by teachers to guide lesson planning. The website also provides downloadable fact sheets about the fungus.