Introduction: Light Microscopy
Among the different types of microscopy, light microscopy has been one of the most commonly used and well-known techniques. The easy availability of instruments, consumables, tissue fixation agents, stains, and other required supplements make it the most reliable tool for high school, university, and college-level students.
Light microscopy has been a standard microscopy technique taught to students across the world. With its little intricacies and tricks, it isn't a very difficult skill to master. Still, students who are first introduced to microscopes face troubles with their operation. There are quite a few novel terminologies for students like magnification, contrast, and resolution which can be perplexing if students don’t know the meanings and differences between each.
Light microscopy is one type of microscopy amongst a range of options in the present time like an electron, confocal, fluorescence, etc. Without knowing the pros and cons of each, students tend to get confused about the choice of microscope that suits their purpose.
There are several plausible reasons why students fear the practical handling of a light microscope. We have compiled all of these reasons for educators to acknowledge and bring solutions to. We also list some of the practical solutions that educators can utilize in their next class to simplify both theory and practical handling for their students. By the end, we’ll share why a virtual lab simulation will prove useful not only for your students but also for you as an educator to deliver concepts more efficiently.
3 reasons why Light Microscopy can be tricky to teach or learn
There are 3 reasons why students dread the topic of the Light Microscopy technique. Acknowledging these issues is the first step toward making the topic more approachable.
1. Confusion related to basic instrument structure and sample preparation
This is the most common reason why students get confused by the topic of light microscopy. Students are often unaware of the different roles that each part of the light microscope serves. This makes them confused or completely forgetful about one or the other parts. Having no idea about the specific roles of a tungsten halogen bulb, diaphragm, mirrors, nose piece, objective lens, eyepiece, stage, condenser, and coarse and fine adjustment knobs could make the light microscope appear like complex machinery with no user manual.
Also, many students aren't sure about the roles of stains and fixating agents. Sample slide preparation is one of the main steps that can’t be compromised if you want to make the most of light microscopy.
2. Difficulty in tracing the path of light due to the lack of interactive tools
Students face difficulty tracing the path of light and are often clueless about how the light illuminates the sample on the stage. Teachers explaining how light originating from a halogen bulb or other low-voltage external source is focused via a condenser onto the stage to illuminate the sample can be difficult in absence of proper interactive tools like flowcharts, illustrations, and video simulations. Further, the lack of microscopes in school and college facility rooms aggravates the situation by eliminating the possibility of physical instrument handling.
3. Too many options
Within the umbrella of light microscopy, there are some specific microscopy techniques based on some differences. For example, there is a bright field microscopy technique and there’s another dark field microscopy technique. Also, depending on the number of lenses used for magnification, there is a simple light microscope and there’s another one called compound light microscope. Modern light microscopes also consist of phase contrast and light fluorescence microscopes. With such a long list of variations within the light microscopy technique, students often get confused and fail to differentiate between the different types.
5 ways to make Light Microscopy a more approachable topic to understand
To address the blocks encountered while teaching the Light Microscopy technique, educators can engage the under-listed solutions in their classes. These can clarify many instrumental aspects of this microscopy technique and its operation. Not only can they make teaching easier for educators like you but will also make lessons clearer and easier to assimilate for your students.
1. Explain the roles of the different parts of the microscope
Since a simple light microscope is the most basic type, educators can first explain the roles of its different parts. This will help their students to adjust and use the instrument to its maximum potential. We provide a few examples of how educators can proceed with this activity.
Light source/Illuminator: The most common light source in light microscopes is a tungsten/halogen bulb which is usually located at the base of the microscope. Some pretty elementary light microscopes used to have ‘reflective mirrors’ that used to focus the ambient or natural light from the surroundings onto the stage.
Condenser: A condenser is used to maximally collect and then focus the light from the light source/illuminator onto the specimen. These are also found beneath the stage and ensure that our specimen is well-lit.
Similarly, you can explain the specific roles of each part of the microscope. This basic understanding can drive out the fear amongst the students related to the handling of this technique and the instrument.
Figure: An image from the Light Microscopy simulation from Labster demonstrating the different parts of the light microscope. Full simulation is available for High School, Professional, and University / College classes.
2. Simplify the lab practices
Since the main practices involved in visualization using a light microscope are fixation and staining, explaining the principle and role of these 2 processes can simplify the subject for your students. You can educate your students about the different fixative agents and their mechanisms of action.
Example: Glutaraldehyde is a commonly used fixative. It is usually used for the preparation of whole cells and tissues. 4% (w/v) paraformaldehyde and a mix of paraformaldehyde with glutaraldehyde are also used as fixatives in light microscopy techniques. Fixation is more common when one is using electron microscopes, but it is also used for light microscopy. The major roles of fixatives are: Ceasing the normal metabolism of the tissue and preservation of the sample.
Similarly, you can explain the roles and different types of stains generally used in light microscopy techniques. Example: Safranin is a commonly used stain for plant tissues while Methylene blue is a commonly used stain for animal tissues.
Figure: An image from the Light Microscopy simulation from Labster demonstrating the sample preparation steps for the light microscopy technique. Full simulation is available for High School, Professional, and University / College classes.
3. Cut to the chase about “physics concept”
The basic principles of magnification, resolution and contrasting images stem from basic physics. We can explain these concepts at the very beginning so that students know how the 2 lenses used in magnification (objective and ocular) come together and increase the microscope’s magnification.
Explaining the difference between ‘magnification’ and ‘resolution’: It's basic physics but many students are confused between the 2 terminologies; magnification and resolution. While the former is the ability of a microscope to make small objects appear larger, the latter is the ability of a microscope to distinguish two microscopic objects from each other. You must pay due attention to this fact and clarify this concept to your students.
After this is clear to the students, you can teach them how magnification using 2 lenses is calculated. For simple light microscopes, the magnification is limited due to the presence of only one lens while the magnification of a compound light microscope is the product of the 2 lenses. Example: If the ocular lens possesses a magnification of 10x while an objective lens possesses a magnification of 4x, the total magnification is the product of the two, i.e., 40x.
Abbe’s equation was first used to calculate the theoretical resolution of a light microscope. Because of the limited resolving power of visible light, the actual resolution of the light microscope isn’t greater than the theoretical resolution.
You can also talk about refraction, concave and convex lenses, and wavelengths of the visible spectrum to further clarify the subject.
4. Contrast it with other microscopy techniques
There is a range of microscopy techniques. While teaching your students about light microscopy, you should educate them about its pros and cons and try to contrast it with other alternative microscopy techniques. This will help them build a comprehensive knowledge system and help them in guiding their choice of technique as per their experimental requirements. You should explain the mechanism underlying the working of all the other microscopes too. You can use the Microscopy simulation, the Confocal Microscopy simulation, and the Fluorescence Microscopy simulation from Labster to further demonstrate each of these techniques to your students.
Figure: An interactive gif from the Light Microscopy simulation from Labster demonstrating the magnification of 100X in the light microscope. Full simulation is available for High School, Professional, and University / College classes.
5. Use virtual lab simulations
Since light microscopy is a convoluted topic for young and early learners and it also has a lot of intricacies, the topic can sometimes be very difficult to teach in class.
Even though educators and teachers are passionate to demonstrate the different aspects of the subject, they struggle to deliver the idea sometimes. We bring virtual laboratory simulations that can ease your process of lecture delivery as well as lab handling sessions. You can make more insightful points as students are rendered with better picture options. The 3D simulations help them better understand the intricacies of operating different types of microscopes.
Your students don’t have to struggle to imagine different colors of fluorophores as our interactive Light Microscopy simulation along with gamification elements come to the rescue. By using this way of active and immersive teaching, our virtual learning platform takes an advent in the field of Science to make the upcoming scientists thorough with the “basics of their respective subjects”.