Responses to common laboratory questions

Questioning goes both ways in the laboratory setting. Students question TA's to make sure that they understand the laboratory material and the steps that they are following. TA's question students to probe the depths of their students' knowledge. Tips for negotiating both lines of questioning are below:

TA's questioning students

Asking students thought-provoking questions makes them more aware of their learning process. Through questions, students are given an opportunity to provide feedback about what they do and don't understand and about what additional information or resources they need to enhance their learning. Good questions:

  • Require students to think, describe & explain.
  • Help students to build their understanding of the experiment and the underlying theory.
  • Promote critical thinking.
  • Draw out points of confusion or concern.

Students questioning TA's

What follows is a list of student questions that are commonly heard in undergraduate science and engineering labs. Click on the questions to reveal some potential responses (R) that would encourage a student to think about the difficulty that they have just encountered and allow them to practice their problem solving skills in the process of figuring out how to overcome it.

Questions about lab equipment
Questions about lab procedure
Questions about accuracy and precision
Questions about lab data and calculations
Questions about lab results

Questions about lab equipment

Q: How do you work this thing?
R: Have you taken a close look at the diagram in the lab manual?
R: At what point in the instructions are you getting stuck?
R: What specifically are you unsure about?
R: Which part of the instrument is particularly confusing to you?

Q: I don’t get how this works.
R: Have you taken a close look at the diagram in the lab manual?
R: At what point in the instructions are you getting stuck?
R: Which part of the instrument is particularly confusing to you?

Q: How do we calibrate it?
R: Let’s take a look at the instructions for calibration.

Q: Have I got this set up right?
R: What makes you think that your set up might be wrong?
R: Have you asked your lab partner? A second opinion might help confirm whether your set up is correct.
R: Let’s take a look at the diagram in the lab manual. Do you have all of the components?

Q: We’re getting some pretty weird readings here.
R: What do you mean by ‘weird’? Can you explain that in more scientific terms?
R: What indicates to you that your readings are ‘weird’?
R: Have you completed all the experimental steps properly? Did any one of them in particular give you difficulty?

Q: Could you take a look at our results? Are they in the ballpark?
(Note: ‘in the ballpark’ is a colloquial term that means ‘in an acceptable range’)
R: In what range do you think the values should fall? How might you be able to figure that out?
R: Are the results of your repeat trials consistent?
R: Did you and your lab partner complete the calculations independently? If not, repeat the calculation separately and see if you come up with the same value.

Questions about lab procedure

Q: How do we know when we’ve let it go on long enough?
R: What signs does the laboratory manual tell you to look for?
R: In the pre-lab talk, I mentioned a change that you would observe visually in your flask. Can you remember what change that was?

Q: How many times should we be repeating this step?
R: Let’s take a look at Section X of your lab manual. I think you’ll be able to find the answer that you’re looking for in this section.

Q: Is there some easier way of doing this?
R: What are you finding particularly difficult about this method?
R: Yes, there are easier ways of doing this. Expensive pieces of equipment have automated many of the steps you’re carrying out by hand. But, working through these steps allows you to experience the principles that underlie the experimental outcomes. It’s these connections that are particularly important and that you want to highlight in your lab report.

Q: Am I doing this right?
R: What makes you think you might be doing it wrong?
R: What does the lab manual suggest you should see at this step? Are you seeing something similar?

Q: I think I messed this part up. Do I have to start over?
R: What makes you think that you’ve completed the step incorrectly?
R: In which specific step do you think you’ve made your mistake? Let’s take a look in the lab manual at the steps that come before and after that one to see how far in the experiment you’ll have to backtrack.

Q: What do we do after this? I forget.
R: What step are you at in the lab manual? Continue from that point on.
R: Confer with your lab partner. Together, you should be able to determine what the next best step might be.

Q: Why are we doing this?
R: That’s a very good question that I’d like to turn over to you. Why do you think this is an important process/step?
R: Think back to last week’s lecture – can you see any connections between this experiment and the theoretical material Dr. X covered?
R: This is a very useful technique. It’s used in a broad range of applications in the field, such as…

Questions about accuracy and precision

Q: What happened to my sample? Why did it change colour like that?
R: At what point in the procedure did the colour change take place? What happened in that step that might have caused this change?
R: How does your product differ from what you expected? At what point did the change occur?

Q: I don’t think I got a pure product.
R: What indicates to you that this might not be a pure product?
R: What impact will these impurities have on your final results?
R: How might you improve the purity of your product at this point?

Q: Does this look right?
R: What are you expecting to observe at the end of this step?
R: How does your product differ from what you expected?

Q: I think we must have messed up. Our data’s looking weird.
R: What do you mean by ‘weird’? Can you explain that in more scientific terms?
R: What specific indications do you have that your data is unusual?

Q: We must have messed up somehow. We’re not getting the right numbers.
R: Let’s take a step back and examine each part of your calculation in detail.
R: Do you have a specific question about the calculations? At which step do you encounter the most confusion?

Q: I don’t think we did the last part right. Can we move on anyway?
R: Where do you think you made your mistake in the last part? Let’s see if we can go back and correct that before moving on.
R: Each part of this experiment builds on the last, so it’s important that we go back and address the mistake in the last section. What were you having difficulty with?

Questions about lab data and calculations

Q: How accurate do we have to be?
R: Accuracy is very important in experimentation and accuracy is dictated by the instrument you use to measure an observable quantity. To how many significant digits did you measure your variables?
R: Your measurements will always deviate slightly from the standard and that’s okay. I talked about acceptable levels of deviation in the pre-lab – do you remember what boundaries I highlighted?

Q: Do you want us to get a real exact value here?
R: I’d like you to be as accurate as possible and accuracy is dictated by the instrument you use to measure an observable quantity. To how many significant digits did you measure your variables?

Q: How’s our data look?
R: Can you be more specific? What about the data concerns you?

Q: Our data’s a little off. Could you take a look?
R: Can you be more specific? What about the data concerns you?
R: Can you define ‘off’ for me in more scientific terms? How is your data not reflecting your expectations?

Q: Have we taken enough data points?
R: How many do you think you’d need to feel confident about your results?
R: Later on you’ll be analyzing the standard deviation of your data. How will having too few data points affect your standard deviation?

Questions about lab results

Q: Is it okay if we’re off a little bit in our calculations?
R: No. There may be variations in your data, but the results of your calculations using those data should be accurate. Are you encountering any specific problems with the calculations?
R: In which step of the calculations do you feel that you’re going off track?

Q: Would you show me how we’re supposed to plot these points?
R: There is a detailed description of the graphing process in the lab manual and we went over the procedure in the pre-lab. Which particular step is confusing to you?
R: Have you checked with your lab partner? Perhaps together, you might be able to determine what the next graphing step should be.

Q: Does our curve look right? Isn’t it supposed to be linear?
R: First let’s take a look at the equation that the data represent. Does that equation imply a linear relationship?
R: The fact that your data doesn’t reflect the expected outcome likely indicates problems in the experimental procedure or data collection. Can you think of any potential sources of error in the experimental design?

Q: What kind of units is it supposed to be in?
R: Take another look at Section X in the lab manual. What units does it ask you for?
R: What are the standard SI units for X?
R: Take a look at the units for the data that you’re inputting. What unit finally results from the combination of those initial ones?