When asked to find a specimen size:

- Find the highest magnification image that totally contains the specimen. In the example below, 100X is too small, 1000X is too big (because the paramecium is bigger than the field of view), but 400X is just right!
- Measure the diameter of the field of view in your image. Be as accurate and precise in your measurements. In this example, it’s 7.2 cm as we measured in class. If it’s an image on paper, not just on your phone, you can draw a line. Or, draw a line using the editing software on your photo app.
- Measure the length or width of your specimen in your image, depending on what you are being asked to find. In the example below it’s the length of a paramecium. It’s 2.9cm here. Draw the line you measured for this as well.
- Set up the magic square formula. Put the quantity and specimen you’re seeking in the top-left spot in the square. Below that put the dFOVmagX symbol. Make a similar set up on the right side of the square as shown below. This is step 1 of your properly formatted calculation.
- Substitute in the known and measured values
**with their units**! This is step 2 and is required in future assignments and tests.
- The step where we see the decimal created from dividing the image values is optional to jot down. I assume you know how to find the final answer with the calculator. It’s here just to see the idea that this paramecium’s length is about 40% of the diameter of the field of view. When you know this value it helps you do a more accurate scientific drawing of a specimen when you are required to do so.
- Step 3 of the required calculation is the final answer after you’ve done your calculations. Since we know our dFOVs were determined using some imprecision, we will round off all final microscopic calculations to the nearest micron (so no decimals in your final answer). Our final answer cannot be more precise than the tools that were used to do the measurements with in the first place.
- Step 4 is a sentence answering the original question that as been asked.

By showing all these steps you are demonstrating your skills and understanding of how you arrived at your final results. In research, this is essential as a scientist must be able to justify how they arrived at their data and conclusions. Prior to publishing any research papers, drafts of lab investigations are sent to fellow scientists for peer review. If flaws are found or key details are missing, the paper must be revised to a sufficient degree or else the work is not published. Scientists are given grant money based on their publications, which is where the saying “publish or perish” comes from.

In our class, when asked to measure and determine the size of microscopic specimens, you are to show your measurements and data analysis and final answer as shown in the format below.