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This manual is a collection of advice, tips, and miscellaneous useful information for teaching assistants. Most of the information was contributed by members of the Columbia Biological Sciences Department. Some of it is from graduate students who served as teaching assistants and some of it is from professors who depended on teaching assistants to help with their courses. Most of this advice was obtained in response to the questions, "What would you tell a new TA?" and "What should a TA know?" The material has been organized by topic so you can look up advice on whatever subject concerns you. Some ideas are repeated in slightly different form under different topics and some cross references are included.

I want to thank all those who contributed ideas to this manual and I welcome additions, corrections and comments. You can call me at X4-4497, e-mail or leave a note in my box, 1104 Fairchild.

1. What does a teaching assistant do?

2. What works & what doesn't.

3. How to avoid passivity

4. Preparation

5. Famous difficulties & misunderstandings

6. How to start class

7. Problem solving

8. Problems with numbers

9. Using the blackboard

10. Explaining

1. The TA discusses the material of the course -- finds out what students are confused about and explains. The trick is to get the students to speak up and to tell you what they need to know so you can zero in on the trouble spots. (See the section on how to avoid passivity.) You don't want to repeat everything in the book or everything the lecturer said in class. It's too boring and slow if you repeat everything, so you have to be selective.

If there are assigned questions or problems, the TA goes over them. If there are no assigned questions, the TA uses the students' questions or covers whatever seems important and/or difficult from the lecture material or readings. The 2 major rules are (1) be selective and (2) be responsive to the students' needs -- find out from the students what they need help with.

2. The TA tells students what's important -- what's stressed on exams, what's worth reading, what to memorize, and so on. Teachers differ a lot in what they expect of the students, and the students get very anxious as a result. A well informed TA can reduce student anxiety and free the lecturer from endless questions about what's on exams and "what are we responsible for?" The TA can usually get the necessary information from the teacher or from last year's TAs in the course. Some very successful TAs have acted very much like coaches on a sports team, urging their students on to victory with tips on exam taking, studying etc. For many students the moral support and encouragement provided by a TA can be as important as the scientific information that the TA provides.

3. Some TAs are expected to present material which is not covered in lecture (or by the lab instructor). This means that some TAs give short lectures and/or lead discussions of articles.

4. A laboratory TA does all of the above and guides the students through the actual experiments as well. The basic point for a lab TA is to be as helpful as possible without hanging over the students' shoulders. There is a big temptation for a lab TA to sit down in one spot and wait for the students to ask for assistance. It is much better to walk around and look for students in need of help. There are two reasons to seek out the students. First of all, students will often ask questions if you walk by, but won't bother to ask if they have to seek you out in your corner. Secondly, it is better to catch them before they mess up than afterwards. So it pays to walk around and look for students who look lost or as if they are about to mess up their experiment.

1. Give the students enough time to collect their thoughts, look through their notes, & respond to your questions. It's ok if there is a pause of a few seconds now and then. If they don't answer a question after a reasonable pause, rephrase the question or ask a simpler one. Don't give in and give the answer yourself -- get it out of them if at all possible. Long, dead silences are boring, but if you stand firm in the beginning and make it clear that you will not do all the talking yourself, the students will get in the habit of talking. (They probably won't talk at first because they are shy, afraid of looking stupid, and/or unprepared.)

If you feel foolish during pauses, do something so you feel busy -- look through your notes, sip your coffee (or glass of water), clean your glasses, etc.

2. Say "I don't want to do all the talking. That's the lecture's job, not mine."

3. Have the students take turns going to the board and working out problems.

4. Go around the room and make them speak in order. In other words, don't rely on volunteers, since the same few students tend to do most of the talking. If you go around the room in an arbitrary order, it's hard on the shy ones, but at least it's fair, and you clearly aren't picking on anyone.

You can have each student in turn ask you a question, or you can have each student "recite" -- that is have each student in turn try to explain a problem.

5. You can ask each student to bring a question to class. To make it concrete, insist that each student bring a 3 X 5 card with a question written on it. You can even stand at the door and refuse to let anyone in without a card.

6. If you have a student who does a lot of talking, you can always say something like "Does anyone but Joe have a question?" Or you can ask a question, and when Joe raises his hand say "No, not you." In other words, make a joke of the fact that Joe loves to talk and that no one else will. A little humor helps a lot, but be careful not to embarrass anyone or make fun of ignorance. Always make jokes at the expense of students who can take it.

1. You need to know the subject you are discussing one layer deeper than you expect to talk about it. In other words you need to know the right answer and why the right answer is right and you should be able to explain why the right answer is right. You do not need to say everything you know -- it's usually better not to say everything you know on the subject, but it is necessary to know more than you plan to say so that you will feel confident.

2. You don't need to know everything! If you are confident, it is ok to say "I don't know" or "It doesn't matter" (if it really doesn't matter). It is much better to admit you don't know than to bluff. If you don't know, and it does matter, say you'll look it up and then do it promptly.

3. It is good to look in advance for trouble spots -- places where confusion, misunderstanding, etc. can arise. (See topic 5 -- famous misunderstandings)

4. When you go over a problem in preparation for class, you should understand

(a) the general principles on which the specific problem is based, not just the answer to that particular problem, and

(b) how to get the answer. The process of getting there is just as important as the result. Remember you are trying to teach the students how to solve problems for themselves. (See topic 7 -- problem solving)

5. Going to lectures is well worth it. It seems very time consuming, but it is much faster than learning all the material on your own, and it is the best way to find out the lecturer's strengths, weaknesses and emphases.

A. Problems of terminology

1. 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.

Another example: The teacher asks "Does burning destroy matter?" and the student says "Yes." The teacher groans and thinks the student is an idiot. But the student is not -- s/he is using the term "destroy" in its ordinary English sense, and the teacher is using it in its technical physics sense. If the teacher's house burns down, the house will certainly be destroyed (in the English sense), even though the atoms that were in the house have not been altered.

2. 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.

3. 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.

B. Other types of common conceptual difficulties

1. 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.

2. 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.

1. Collect Questions

Ask the students for specific questions or topics that they want you to go over. Write the questions &/or topics on the board. Do not answer the questions as they are asked. Keep collecting questions until you have a reasonably long list. Once you have the list of questions/topics on the board, you can look at the list and decide what to do first. You can go over the questions in order of importance, or logical order, or the order they were covered in class. Do whatever seems sensible to you. As you cover each question, check it off the list.

The first few times you do this, it will be very difficult to get the students to speak up. So be patient and give them plenty of time to come up with questions. Wait until you have a decent length list before you start answering the questions. (See topic 3 -- how to avoid passivity.)

This method works best if you can look at the list and see instantly what topics need to be discussed. So be sure your list is self explanatory. If the student says "Do problem 5" don"t just write "#5" on the board -- add a few words so you and the students can remember what problem 5 is about. For example, write "#5 -- crossing over" or "#5 -- protein synthesis" or whatever. If the student asks a long question, you don't have to write it out word for word -- just write enough on the board so everyone can remember what the question is about. For example, you don't have to write "Why is the maximum value for recombination frequency 50%?" You can just write "Max RF" or "why RF < 50%?"

2. The Old Card Trick

Ask each student to come to class with at least one question written on a 3 X 5 card. Collect the cards at the beginning of class and use the questions to organize the session. One way to proceed is to spend a few minutes reading the questions silently. Then you can write the good questions on the board, as above, or read them outloud. Another way to start is simply to shuffle the cards and read one out loud at random. Once you have picked the question(s) to go over, you can answer the questions yourself, or you can let the students answer each other's questions.

3. Ask Them a Question

Ask the students a question, preferably about an experimental situation. For example: Suppose you find a one foot black and white sphere in Riverside Park and you suspect it is a new organism. (a) If it really is alive and not an abandoned soccer ball, then is it more likely to be a prokaryote or a eukaryote? (b) How can you decide (experimentally) if your answer to (a) is correct?

After you pose the question, you can then ask the students

(a) What do you know that's relevant to this question/situation?

(b) What do you need to measure or find out?

After you have discussed what information you need, you can then go over how to use the information to get the answer. This sort of exercise will reveal what level of knowledge the students have (what facts they know) and their level of insight (how good they are at applying the facts). It will also allow any confusions the students have to surface.

4. Pair them Up

This method works well if the teacher has assigned questions, but the students have not had time to go over them. In other words, this works even if the students are not prepared. Divide the students up into pairs or small groups and have each group go over the assigned questions and prepare an answer sheet for the entire group. (You can also do this by making up your own questions and handing them out.) Allow about 1/2 hr. minimum for the students to go over the questions. While they are working, you should walk around the room and listen to what they are saying. Don't sit up front and wait for them to come to you. If they are stuck, help them. If they are fooling around, prod them into getting down to work. If they have made mistakes, ask them leading questions. At the end, collect the answer sheets and go over any points that are still unclear.

1. Before you try to explain a problem, ask yourself "What is the point of this problem or experiment?" Is it to show how to use a formula? Get certain facts or relationships straight? Gain familiarity with a concept or procedure? Make certain distinctions clear? Once the answer is clear in your own mind, it will be much easier to explain the problem and much easier for you and the students to see what is important and what is trivial.

2. A common response to a complicated problem is, "How the *?#*#*! am I supposed to answer/solve this?" So go over (a) what information is needed to solve the problem and then (b) explain how you use the information. Students often know the right information but they know so much irrelevant information that they can't pick out the right pieces. So go over how you figure out the answer to "What do I know (or need to look up) that's relevant?" Once you have shown the students what information they need, go over how to use the information to get the solution. It is important to realize that explaining how you get the solution is different from explaining the solution itself. So be sure that how you got the answer is just as clear as the answer.

1. The case of the overmathematical student

Some students are very at ease with numbers and greatly prefer numerical plug-in problems to thinking problems. These students tend to miss the biological point because the are so busy manipulating the numbers. They can solve anything that uses a formula, but tend to overlook the meaning of the formula. With these students you have to be careful that you don't lose the biology in the number crunching.

2. The case of the unmathematical student

Some students are just the opposite -- they prefer words and discussions to numbers and turn pale every time a formula appears. These students often get the general idea but have trouble doing specific numerical examples. These students are often unaware that biology is a quantitative science -- they think it is all descriptive and are shocked to find out they will have to do problems with numbers.

3. Most classes have both types of students

Remember that you probably have both kinds of students described above in your class and that you will have to explain the biology to the mathematicians and the math to the biologists.

4. Estimate first and calculate later (if necessary)

Encourage students to estimate and use their heads instead of relying solely on their calculators. Estimating makes the math seem less formal and intimidating to some of the nonmathematical, and it discourages the overly mathematical from plugging blindly into formulas. In other words, using estimates often helps keep the focus on the biology instead of the math. If students learn to estimate, they can often avoid gross errors that lead to absurd results.

1. How to write on the board

A. Both words and diagrams should be large and clear. There is lots of big soft chalk in room 500.

B. Use colored chalk as much as possible. If you can't find any, buy some and get petty cash to repay you (ask in room 600).

C. When you have filled up the board, erase a large area thoroughly before continuing. Don't keep writing in the corners and edges of your old, filled up board.

D. Use diagrams as well as words (see below).

2. Using Diagrams

Diagrams and pictures are very helpful, both to you and to the students. A diagram helps the students because it can convey relationships that are almost impossible to put into words. It helps you, because you can refer to it over and over. Once you have the picture on the board, you can point to it and avoid using the technical terms or you can point and use the terms at the same time as reinforcement. So draw as much as you can. Artistic talent is not required, but remember the colored chalk and draw big, clear pictures.

To put it another way, drawing allows you to show what you mean in pictures at the same time that you say what you mean in words. So drawing a diagram and explaining it as you go along makes the best use of the board. It is much better than just writing down the words that you say.

3. What to write

Don't write everything you say on the board. It is good to write all the important points and terms on the board, but it is not necessary to write down all the details. It usually works best to write a term or draw a picture and then explain verbally.

4. Timing

Drawing carefully, writing clearly, and erasing properly all take time. Don't worry about wasting time. A pause is usually welcome if the general pace is lively. Remember that the students are writing things down, and that they usually are writing more than you are, since they are copying your lists and pictures and taking notes on your explanations. So they sometimes need a pause in order to catch up with you.

5. Miscellaneous Advice

A. When you are facing the blackboard, stop talking. In other words, don't talk into the blackboard.

B. When you write an important point or term, and then explain, don't stand in front of what you have just written.

C. If your English pronunciation is poor, draw and write more on the board.

1. Use a picture or diagram instead of (or in addition to) words.

2. Avoid pronouns and use nouns instead.

Don't say "it" -- say "mRNA" or "gene" or whatever. You should be careful not to use too many pronouns yourself and you shouldn't let the students do it either. For example, suppose a student says "The gene is transcribed and then it goes to the cytoplasm and is translated which uses tRNA and mRNA." Now the student may or may not understand how genes are expressed, but you can't tell whether s/he knows or not, because "it" could mean gene or mRNA and "which" could mean transcription or translation. In this example, the student may know the correct answer and just be using poor English by accident, or the student may not know and be using unclear language on purpose to hide his or her confusion. Alternatively, the student may not even realize that s/he is unclear in his or her own mind. So if you want to express yourself clearly, and you want to be sure that your students have everything straight, use as many nouns and as few pronouns as possible, even if it sounds a little repetitious. And make the students talk in nouns too.

3. Before you start to explain a topic or problem, find out where the student is stuck. This will save you from wasting time and energy explaining things that are clear and allow you to zero in on the real problem.

4. Explain a short piece of a problem at a time, and then don't go on until (a) you are sure that everyone understands what you explained and (b) you are sure that you need to explain the rest.

For part (a) asking "Does everyone understand?" doesn't usually get a satisfactory answer. You have to look at the students' faces or ask a question about what you have just said in order to find out if they understand.

For part (b) you may discover that you don't have to explain the whole thing because the part you just explained was the only hard part and the student has now come "unstuck." (See point 3 above.)

5. If you don't know the answer, go look it up for next time, or look it up right on the spot if you have the right book and can figure it out right away. You aren't expected to know everything, but you are expected to be able to figure everything out eventually. (See preparation section.)

6. When a student asks a specific question, try to answer it without going over a lot of background material. If a student asks you to explain hydrophobic bonds, don't start with atomic structure. Assume s/he knows what electrons and covalent bonds are, and proceed from there. If there is any question about where to start explaining, ask the student. (See point 3 above.)

Department of Biological Sciences

Columbia University

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New York, N.Y. 10027-7004

212-854-4497

URL: http://www.columbia.edu/cu/biology/faculty/mowshowitz/index.html

html translation by: Mark Kleinman