I just looked over the assignments that have been handed in so far, and I have a couple additional notes:
1. For each combination that reacted during the first week of the experiment, write a balanced chemical equation. For reactions that formed complex ions, you can just note that the product of the reaction is “complex ion”. Organize your reactions clearly in the order they appear in the lab manual, starting with all the reactions involving Ni(NO3)2(aq), then all the reactions involving Pb(NO3)2(aq), etc.
>>If a combination did not react, you do not have to write a reaction. You can write "full formula/molecular equations" or net ionic equations, it's your choice for this experiment.
>>DO NOT WRITE YOUR CHEMICAL EQUATIONS AS ONE BIG PARAGRAPH!! The point of organizing them is to make them easier for you to write them all and for me to follow/read/grade them. If you write them as a massive block of text, I will not read them, and you probably won't earn many points. One equation per line, with appropriate subscripts and/or superscripts, state labels, parentheses, etc.
>>"in the order they appear in the lab manual" is not a joke or a suggestion. If you do not organize your chemical equations in the correct order, I will not spend much time hunting through your randomly-ordered equations to try to find them all. I will assume they are not there and you probably won't earn many points.
2. Identify the contents of each of your unknowns with a brief explanation. For example, “Unknown M4 contained phosphoric acid because it generated heat when reacting with bases and formed a precipitate with transition metal ions.”
>>Each set of unknowns had a letter AND a number associated with each sample. If you do not identify each unknown with a letter AND a number, it is wrong.
If you've already handed in an assignment and would like to fix some of these problems (that would be a really good idea...), you can turn in a revised assignment. If you choose to turn in a revised assignment, you must very clearly and obviously write or type "PLEASE GRADE THIS ASSIGNMENT AND DISCARD THE PREVIOUS ONE" on your assignment (you might even want to use a highlighter...). If you do not clearly and obviously indicate that you want the "new" assignment graded, I will grade the first assignment that was submitted.
2012-10-30
2012-10-26
Improving your scores
A few people have express concern over their scores on hand-in assignments for lab. There's definitely room for improvement, but a single low score will not have that much impact on your grade, so keep at it. There are a couple general pointers that I've been giving students to help improve your hand-in scores:
1. Make sure you're answering the questions. I lot of people have been losing points because they're not really answering the question that's being asked, or they're answering part of it without really exploring WHY the answer they're giving is correct. Most of the questions on the hand-ins require a bit of explanation, make sure you're explaining your answers, not just describing an observation. If your answer takes up fewer lines of text than the question, you're probably not answering the question completely. That doesn't mean I want everyone to write a book to answer each question, but you should be trying to answer the whole question.
2. Don't lose points for mechanical reasons. Lots of people are "forgetting" to include graphs or data tables, or just showing a result without showing the calculations that went into that result. {No, your Lab Assistant did not tell you to turn your only copy of the graph in with your carbons...} Assignments must be typed (including formulas, equations, calculations, etc.), if you hand-write your assignment you'll probably get a zero. Circle or highlight your section/lab assistant so I can keep track of different piles of assignments or you'll lose 5 points. Assignments are due at very specific times listed in the course syllabus, repeated late or missing assignments will cost you a LOT of points and you'll very quickly fair the course. Grammar and spelling are important even though this isn't an English class; if your answer is very clear and easy to understand, it's easier to grade.
3. Take advantage of your time in lab. Many students finish the "wet" part of the experiment and then run out the door. If you finish early, make sure that you take a look at the hand-in assignment and discuss the questions and answers with your partner before you leave. If you're not sure about a question, ask.
4. Take advantage of your lab instructor(s). If you're working on a hand-in and you're not sure about what a question is asking or how to interpret your data, ask your instructor. This is more effective if you have a question that shows you put some thought into it, like "I started trying to analyze my data by calculating how many moles of each substance were used in each reaction, and then I calculated the mole fraction. What's the next step?", rather than "I don't understand how to do any of this. Where should I start?"
5. This is similar to #3... Start your assignment early so you have time to ask questions if necessary. If you wait until Tuesday night to work on an assignment that's due at noon on Wednesday, you'll never be able to ask a question and expect to get an answer in time to turn in the assignment on time.
Those are probably the big ones. If everyone did those things, everyone would be getting MUCH better scores on hand-in assignments. Something that students don't often know... It is MUCH MUCH MUCH easier to grade assignments that are correct! I don't ask questions with the intention to be sneaky, or tricky. It's not my goal to see how many points I can take away. I would be giggling with glee if everyone handed in assignments that were mostly (or totally) correct and complete. I really do want you to succeed, but that does not mean that I'm going to give you points or grades that you don't earn by doing the assignments and thinking about the questions you are answering.
1. Make sure you're answering the questions. I lot of people have been losing points because they're not really answering the question that's being asked, or they're answering part of it without really exploring WHY the answer they're giving is correct. Most of the questions on the hand-ins require a bit of explanation, make sure you're explaining your answers, not just describing an observation. If your answer takes up fewer lines of text than the question, you're probably not answering the question completely. That doesn't mean I want everyone to write a book to answer each question, but you should be trying to answer the whole question.
2. Don't lose points for mechanical reasons. Lots of people are "forgetting" to include graphs or data tables, or just showing a result without showing the calculations that went into that result. {No, your Lab Assistant did not tell you to turn your only copy of the graph in with your carbons...} Assignments must be typed (including formulas, equations, calculations, etc.), if you hand-write your assignment you'll probably get a zero. Circle or highlight your section/lab assistant so I can keep track of different piles of assignments or you'll lose 5 points. Assignments are due at very specific times listed in the course syllabus, repeated late or missing assignments will cost you a LOT of points and you'll very quickly fair the course. Grammar and spelling are important even though this isn't an English class; if your answer is very clear and easy to understand, it's easier to grade.
3. Take advantage of your time in lab. Many students finish the "wet" part of the experiment and then run out the door. If you finish early, make sure that you take a look at the hand-in assignment and discuss the questions and answers with your partner before you leave. If you're not sure about a question, ask.
4. Take advantage of your lab instructor(s). If you're working on a hand-in and you're not sure about what a question is asking or how to interpret your data, ask your instructor. This is more effective if you have a question that shows you put some thought into it, like "I started trying to analyze my data by calculating how many moles of each substance were used in each reaction, and then I calculated the mole fraction. What's the next step?", rather than "I don't understand how to do any of this. Where should I start?"
5. This is similar to #3... Start your assignment early so you have time to ask questions if necessary. If you wait until Tuesday night to work on an assignment that's due at noon on Wednesday, you'll never be able to ask a question and expect to get an answer in time to turn in the assignment on time.
Those are probably the big ones. If everyone did those things, everyone would be getting MUCH better scores on hand-in assignments. Something that students don't often know... It is MUCH MUCH MUCH easier to grade assignments that are correct! I don't ask questions with the intention to be sneaky, or tricky. It's not my goal to see how many points I can take away. I would be giggling with glee if everyone handed in assignments that were mostly (or totally) correct and complete. I really do want you to succeed, but that does not mean that I'm going to give you points or grades that you don't earn by doing the assignments and thinking about the questions you are answering.
2012-10-09
"Show your work" and "Explain"
In every field and for every instructor, there are certain instructions and questions that may not be explicitly stated, but are always implied. The two that I see people having the most consistent problems with are:
1. "Show your work" - If you are doing a calculation, you must ALWAYS show your work. If a question asks you to calculate the concentration of a solution, the answer is never just "1.18M". Show how you got to that number. You're doing it anyway, you should show it. If you're not doing it, then you're either "borrowing" an answer from someone else or guessing. Show your work. Sometimes, the way the question is worded might make it seem like you don't have to show your work ("What is the concentration of solution A?"), but you still need to show your work. The only real exception to "show your work" is for exceptionally trivial calculation, like adding up a molar mass (although you still should include the correctly balanced formula for anything you're adding up a molar mass for) or taking an average (if you really want to show the steps in taking an average, that's OK, but "average" is a standard enough operation that I don't require you to show your work). How do you decide if something is trivial or common enough that you don't have to show your work? One quick way to check is if the units have to be changed or transformed during the calculation. If the units change, show your work. When in doubt, show your work. If you're not sure, show your work. Even if you're really brilliant, show your work.
1a. "Show your work" = "Show your units" - This is another one that should be implied... In chemistry, there are a couple quantities that are unitless (pH, equilibrium constants), but the VAST majority of numbers should include units. If you do not show your units, you have not shown your work. Always show units on every number that has them. THE ONLY EXCEPTION is in tabulated data where the units can (and often should) be included in the column heading of the table rather than on each individual number.
2. "Explain" - If science was only used to answer the "what" aspects of our daily lives, it would be pretty boring. Science answers the "what" AND the "why". The "why" is always implied. This is the text analog of "show your work". I do not tend to ask questions that I feel can be answered in 1 word or a short phrase. I want to see an explanation of why the answer you gave makes sense in relation to the data you have collected. This does not mean that you have to write a page and a half to answer every question, but it does mean that a sentence or two (or more) is probably required. Support your answers with meaningful data or other explanations, it makes for a much clearer answer.
1. "Show your work" - If you are doing a calculation, you must ALWAYS show your work. If a question asks you to calculate the concentration of a solution, the answer is never just "1.18M". Show how you got to that number. You're doing it anyway, you should show it. If you're not doing it, then you're either "borrowing" an answer from someone else or guessing. Show your work. Sometimes, the way the question is worded might make it seem like you don't have to show your work ("What is the concentration of solution A?"), but you still need to show your work. The only real exception to "show your work" is for exceptionally trivial calculation, like adding up a molar mass (although you still should include the correctly balanced formula for anything you're adding up a molar mass for) or taking an average (if you really want to show the steps in taking an average, that's OK, but "average" is a standard enough operation that I don't require you to show your work). How do you decide if something is trivial or common enough that you don't have to show your work? One quick way to check is if the units have to be changed or transformed during the calculation. If the units change, show your work. When in doubt, show your work. If you're not sure, show your work. Even if you're really brilliant, show your work.
1a. "Show your work" = "Show your units" - This is another one that should be implied... In chemistry, there are a couple quantities that are unitless (pH, equilibrium constants), but the VAST majority of numbers should include units. If you do not show your units, you have not shown your work. Always show units on every number that has them. THE ONLY EXCEPTION is in tabulated data where the units can (and often should) be included in the column heading of the table rather than on each individual number.
2. "Explain" - If science was only used to answer the "what" aspects of our daily lives, it would be pretty boring. Science answers the "what" AND the "why". The "why" is always implied. This is the text analog of "show your work". I do not tend to ask questions that I feel can be answered in 1 word or a short phrase. I want to see an explanation of why the answer you gave makes sense in relation to the data you have collected. This does not mean that you have to write a page and a half to answer every question, but it does mean that a sentence or two (or more) is probably required. Support your answers with meaningful data or other explanations, it makes for a much clearer answer.
Subscribe to:
Posts (Atom)