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| Famous Difficulties & Misunderstandings |
Problems of terminology
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Confusing technical meanings and ordinary meanings of words
Some scientific terms have technical meanings that are very different from their commonsense meanings. For example "spontaneously" in chemistry does not mean "very quickly" or "all by itself" -- it means "without net input of energy." Unfortunately, in common English, spontaneously means "all by itself" and often also "very quickly." So students think spontaneous reactions occur rapidly and/or without an enzyme. This type of difference between technical and ordinary meanings often leads to a lot of confusion, because the TA, book or lecturer is using the term in the technical sense, while the student is using the same term in its nontechnical, commonsense meaning. Even when the student tries to use the term correctly, s/he is often confused by the connotations that the word has in common usage.
Some scientific terms have technical meanings that are very different from their commonsense meanings. For example "spontaneously" in chemistry does not mean "very quickly" or "all by itself" -- it means "without net input of energy." Unfortunately, in common English, spontaneously means "all by itself" and often also "very quickly." So students think spontaneous reactions occur rapidly and/or without an enzyme. This type of difference between technical and ordinary meanings often leads to a lot of confusion, because the TA, book or lecturer is using the term in the technical sense, while the student is using the same term in its nontechnical, commonsense meaning. Even when the student tries to use the term correctly, s/he is often confused by the connotations that the word has in common usage.
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Using words that have technical meanings and not even realizing it
Some ordinary English words are used as technical terms, as explained above, but experienced scientists (such as graduate students and lecturers) are so used to using these words that they often forget that these words have special meanings. So the scientists don't define the terms and are surprised when the students don't know what they mean. For example, what is a "strain" of bacteria? Do all bacteria of the same strain have the same genes &/or alleles? Are the genes in the same order? Are all bacteria of one strain of the same sex? A graduate student who works with bacteria will consider these questions so obvious that s/he will not realize that the answers are not common knowledge.
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Getting confused between similar but not identical terms
Certain terms seem to be difficult to get straight, for example, gene vs allele and chromosome vs chromatid. There are many such pairs of terms that are very similar in meaning and that are often used sloppily even in scientific writing (and speech). To make it worse, some of these terms are synonyms in common speech, such as "inhibition" and "repression." A good way to clear up confusion is to "compare and contrast" -- compare what is similar between the two terms and contrast what is different.
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Other types of common conceptual difficulties
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Finding unlikely &/or complex solutions when ordinary, simple ones will do
There is a saying in medical school: "When you hear hoofbeats in Central Park, you don't think of zebras." In other words, when you hear hoofbeats in the park it is probably a horse, even though it could be a zebra. A person who thinks it is probably a zebra does not understand the situation. When solving problems, always look for the "horse" -- the simple, obvious solution, before you starting worrying about the "zebra" -- the possible, but unlikely solution. Students often come up with very improbable (but possible) answers, and don't understand why their answers are unlikely or why unlikely answers are not as good. Usually their problem is a lack of general background -- if you don't know much about New York, you might not realize that horses are relatively common here and zebras are rare.
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Not seeing how the parts relate to each other or to the whole
Students often understand what certain items are, or what they do, but do not understand how the items relate to each other, or how the details relate to the big picture. For example, students may understand the structure of DNA, that genes are made of DNA and that chromosomes carry genes, but they may have trouble figuring out how the DNA fits in the chromosome. (How many copies per chromosome? How many strands? What's a strand?) As another example, students may understand how DNA is replicated, transcribed, and translated, but they still may not understand how a gene controls a trait. So you may need to explain "up" or "down" how the parts relate to the whole -- up, how the item under discussion fits into something bigger, and down, how the item is made of smaller things. For example, if you are discussing genes, you should be prepared to go "up" to chromosomes, genomes, traits, etc., and "down" to DNA, codons, nucleotides, and bases.
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