Analysis by Kyle Morrison, 06/22/20
For a more formal version, see .
Retrieved from https://bitesizebio.com. Species unknown, but illustrates the point.
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Across 50 compiled/images, tally hIPSCs in Interphase and in each stage of mitosis.
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Don't count cells not fully in view.
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Do count cells in telophase as one cell.
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Aggregate all usable student data (n = 82).
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Plot the average counts (with standard deviations) vs cell cycle phase for each image (50 bar charts!).
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Plot overall average counts (with standard deviations) vs cell cycle phase.
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Plot average residual magnitude (how far off the answer key were the students?) vs image number for each cell cycle phase.
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Examine compiled/images students were the most off on.
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Yellow Line - Answer Key values.
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Students were more conservative in identifying Interphase.
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Yellow Line - Answer Key values.
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Students didn't get worse as the assignment went on (cool!).
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Prophase and Prometaphase have the most false positives.
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Metaphase and Prometaphase are often confused (compare averages around Image 30).
- Again, lots of variability in Interphase, particularly at Image 20 (more on this later).
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Unsurprisingly, Prophase has the largest standard deviations.
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Anaphase is the phase the students did the best on.
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4 bars around Image 15 are almost identical for Prometaphase and Metaphase, further evidence students are mixing them up (more on this later).
- Looks like it might've given the students trouble just because there are a LOT of cells in view.
- Looks like it might've given the students trouble just because there are a LOT of cells in view.
- The answer key missed identifying the Prophase on the right, and the students might have picked up on this one, missed it, identified the Prometaphase as Prophase, or some combination.
- Looks more like misclassification based on the raw data, given both vary a lot here.
- The answer key says Metaphase, but this looks like Prometaphase, which is presumably what the students said.
- Looking at the raw data, it's not clear what happened. Perhaps Anaphase and Telophase mixups combined with Prophase/ Prometaphase/ Metaphase mixups?
- The answer key says Metaphase, but this looks like Prometaphase, which is presumably what the students said. The middle cell does look like it could be late prophase, though, with more like two yellow blobs than one.
- Looks like the students called Prometaphase and Prophase a lot, which matches what the image looks like. Also some mixups of Anaphase/Telophase for good measure.
- Looks like a classic case of "Anaphase or Telophase?"
- Yup.
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Looks like a classic case of "Anaphase or Telophase?"
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Perhaps the cell on the far right that has a bright yellow spot is prophase-like?
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Yup.
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The data supports the idea that the students thought at least something in here was prophase (the answer key disagrees).
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Students were more conservative in identifying Interphase.
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By difference from the answer key (residual magnitude), visual inspection, and my experience grading, the order of rising difficulty: Anaphase, Telophase, Metaphase, Prometaphase, Prophase.
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Interphase was "technically" the most difficult, but I'd chalk this up to being more stringent with counting than to misclassifying Interphase as, say, Prophase.
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Even lab staff, experienced and new, can go back and forth on "proper" labeling. Real compiled/images != diagrams.