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Teaching, Learning, and Grading in Science Labs

In this page — which is part of a wider range of ideas` about education in labs — we'll look at relationships between teaching, learning, and grading.  Here is a condensed summary of the full-length version:
 
 

Goal-Directed Design of Lab Instruction

To help students in science labs learn scientific concepts and thinking skills, you can use a goal-directed designing` of Learning Activities (to provide experience with valuable ideas-and-skills) and Teaching Strategies (to help students learn more from their experiences).  You can find Learning Activities in your current labs — by looking for experiences, both short-term (in a single lab) and longer-term (in a set of labs), that are opportunities for learning — and by designing new Learning Activities for current labs or in new labs.

With an effective designing of instruction there will be mutual support between our Goals (for what to learn) and students' Motivations (to learn) and their Learning Activities (opportunities to learn) that include Evaluation Activities to accurately measure ideas-and-skills that are the educational goals, so they have been the focus of teaching and learning.    {more in full-length section}

 

In labs, a common Learning Activity is a Student Response (by asking or answering questions, showing data, doing calculations, solving mini-problems,...) that is discussed with the teacher, or is written in a report.  We'll look at labs in which students only listen-and-talk, or only write, or do both in hybrid labs that combine the best features of discussions and reports, plus exam questions.    {more}

 
 

Advantages of Discussions

Feedback:  The main benefit of using discussions is the high-quality formative feedback — including guiding and reflection requests — that teachers can provide more easily and effectively by using verbal feedback (detailed, customized in two-way conversation, and immediate, when students are thinking about their ideas & actions) instead of written feedback (with much less detail, and delayed until after the lab).    {more}

Teacher versus Judge:  In a related benefit, a discussions-only lab (without a written report) lets a teacher focus their full attention on teaching, not judging.  If they withhold information — as in responding to a student's question with a partial answer or a hint, or by asking another question — their motivation is pedagogical, to challenge students and let them think so they will play a more active role in their own learning.  The withholding isn't due to worries about being unfair by giving too much information to some students (but not others) about a question that later will be used to assign grades on a lab report.   /     {more about Teacher vs Judge plus the option of Grading Discussions (as Oral Exams)}

 

Discussions are Fun:  Usually, student/teacher discussions (their interactive idea-based conversations) are enjoyable for students and teachers, for a variety of intellectual & social reasons.   Asking students to write reports does not mean “no discussions are allowed” (*) but when student/teacher discussions are not scheduled they are less likely to occur, and to have significant ideas-and-skills content.  And grading reports will produce "teacher versus judge" tensions.   /   Of course, Learning Activities should include student/student discussions, but a teacher who wants individuals to be accountable for their own work (in graded reports) may want to restrict the totally free flowing-of-ideas between students.

Grading Reports is Not Fun:  Most teachers don't enjoy grading lab reports because it produces a small amount of satisfaction,* and requires a lot of time, so it has a low ratio of “personal satisfaction / time invested”.   /   * A teacher will have low satisfaction if they think their grading is not very effective in helping students learn ideas & skills, due to the minimal-and-delayed feedback.  And also because grading reports usually requires a lot of time to make only a small difference in a student's course grade, compared with quick-and-easy decisions about points on a quiz or exam, and the larger “spread between students” on a typical quiz or exam.   But the grading experience can improve if we Design for Grading, as explained in... {more about grading reports}

 

Advantages of Written Reports

Motivation:  The main benefit of using written lab reports is the extrinsic motivation (of working for a grade) that is an important part of the total motivation for most students, and is missing in a discussion-only lab if all students get the same grade, with full credit for discussions during a lab.  A lab report provides accountability, giving students responsibility and a feeling of ownership for their labwork.    {more}

Pacing:  A lab with scheduled discussions has an imbalance of supply-and-demand, with one teacher and many students.  This problem cannot be eliminated.   But it can be reduced if you:  ask students to form larger groups, or do some discussions with several groups;  improve your skills in using lab time more efficiently;  design labs so discussions are spaced evenly throughout it, and so students can do productive activities if they must wait;  move some discussions into a report (with a hybrid lab) to reduce the number of discussions, and add another "productive activity" while waiting.    {more}

Quality of Teachers:  In a discussion-based lab, the learning experience of students depends on the quality of their teacher, so... what happens if they get a lower-quality teacher?  This question — which is important for a large college course with many labs, taught by many TAs who are usually graduate students with a wide range of teaching abilities, experiences, and motivations — is examined in the full-length section {more} along with links to "a wider range of ideas [re: uniformity, normalizing, weighting, collaborating,...] about learning in labs."

 
 

Hybrid Labs — Combining the Best of Both

The sections above` describe advantages of labs with only discussions (better formative feedback, less tension between teaching & judging, more fun during discussions, less non-fun while grading reports) and with only reports (more extrinsic motivation, no problems with pacing of discussions, perhaps fewer problems due to lower-quality teachers).    {more}

Now we'll look at the benefits of designing hybrid labs that combine the best features of discussions and reports, plus pre-lab & post-lab testing.

 

Moving Responses:  To decrease the disadvantages of a pure lab (with only discussions, or only reports) you can convert it into a hybrid lab by moving some responses from discussions into a report, or from a report into discussions, or from either into pre-lab or post-lab testing.

• A written response, previously graded in a report, can be moved into a discussion.  Or you can decide that only some aspects of a written response will be in a scheduled discussion (to adjust the level of difficulty for the response)* so all students will have the same information when they write a response that is graded.   Or, for some written responses a teacher can let students ask for an early grading;  the teacher examines the response and gives a thumbs up (ok as-is) or down (not ok) or sideways (partially ok), and then students can revise their answer, perhaps with some guiding about how to revise.   /   Another way to "adjust the level" is by designing a series of related response-problems that gradually become more difficult, or that guide students' thinking in productive directions to help them learn useful ideas-and-skills.

• Similarly, some oral responses can be moved (partially or totally) from discussions into a report.

In a hybrid lab that already is part-discussions and part-reports, you can “shift the balance” by moving some responses one way or the other, into discussions or into reports.

 

Options for Grading Labs:  We can grade reports, discussions (but should we?), pre-lab quizzes, and post-lab questions (*) in regular tests (quizzes, exams) or special lab-tests with oral or written responses.  Some labs can have built-in accountability for qualitative work (identifying an unknown chemical,...) or quantitative work (finding a solution's concentration,...).  Any of these grading-inputs can be included in the lab grade for a course, and we can ask "How much should lab grades be weighted?"

* This post-lab testing will motivate students to view their labwork (including discussions & reports) as opportunities to learn ideas-and-skills that later will be tested.  But it's difficult to write exams that adequately test higher-level thinking skills, in labs or in general.

 

 

Here is a closer examination of ideas that are summarized above.

 

Goal-Directed Designing of Lab Instruction

This page is a condensation of the main ideas from Teaching Scientific Methods of Thinking in Science Labs which begins with a worthy goal:  "A science lab, where students can do science and think about science, is an ideal place to teach scientific thinking skills.  By a creative use of goal-directed thinking activities in classroom labs, teachers can help students learn some of the thinking skills used by scientists in research labs."   How?

We can use a goal-directed design of curriculum` for all education, including labs, by defining goals for desired ideas-and-skills, and designing instruction with learning activities and teaching strategies that will provide opportunities for experience with these ideas & skills, and will help students learn more from their experiences.  When we design instruction, our "learning activities and teaching strategies" should include goal-directed evaluation activities that are guided by teaching strategies for why, how, and when to evaluate.

The Context of Labs:   • Usually labs are part of a wider-scope course, and are designed to support the course.   • This can be supplemented by reversed inspirations to make other aspects of a course support the goals for learning in labs.   When both of these occur (• •) there will be mutual support between the lab and non-lab parts of a course, with each helping to make the other more effective.

 

The rest of this page is a revision-and-condensation of ideas from "Teaching Scientific Methods of Thinking in Science Labs" about relationships between teaching, learning, and evaluating.

 


 

Formative Feedback – in Discussions and Graded Reports

In labs, a common Learning Activity` — an experience that promotes thinking and learning — is a student response (such as asking or answering questions, showing data, doing calculations, or solving mini-problems) that is written in a lab report, or discussed with the teacher, or some of each.  What are the benefits of asking students to write, or to talk-and-listen?  Based on my experience in teaching labs at two UWs, a little in Seattle and a lot in Madison:

Compared with lab reports, I think discussions are usually more educationally effective and more fun.  Most students agree.  Why?  Conscientious teachers want to provide high-quality formative feedback to help students learn, which is easier and more effective with verbal feedback (detailed, customizable in two-way conversation, and immediate, when students are thinking about their ideas & actions), compared with written feedback (delayed for too long, with much less detail) that also requires extra time for the teacher/grader.

 

Here is a major teaching-and-learning activity that is used in discussions (for a brief time or a longer time) during labs:

By using a reflection request, a teacher can direct students' attention to “what can be learned from an experience,” thus encouraging them to think about what they are doing, what they can learn, and why they should want to take advantage of this valuable opportunity.  A reflection request can help students improve the quality of their concentration by moving them from a minimally-aware mode (of just “going through the motions”) to a more-aware mode that is more effective for learning.  In this way a teacher can help students convert their potential opportunities for learning into actual experiences of learning, to help students learn more from their experiences.   {quoted from "Teaching Scientific Methods..."}

The Timing of Reflections:  Typically, a reflection request is much more useful when it occurs during a lab because that is when students are thinking-and-doing.  A request for reflection usually is much less effective later (when a graded lab report is returned after the lab is over) although this also can be useful, especially if it's combined with a post-lab explanation or discussion.

 

But... even though lab discussions are very useful (for promoting reflection and in other ways) and I prefer instructional design that encourages discussions and makes them more effective, some responses are better in writing.  And written lab reports help decrease the problems of motivation and pacing that tend to occur in labs with only discussions.  Therefore, I recommend hybrid labs that combine discussions and reports, plus exam questions.

 


 

Below are some thoughts about teaching-and-evaluating in labs by using only discussions and only written reports.  I will describe some of the strengths & weaknesses of each approach, the advantages & disadvantages.  I will not adopt a “debater's mentality” by trying to show that one approach is clearly superior by building the strongest possible argument for it, by emphasizing its advantages and ignoring its disadvantages.  After five sections — about Learning & Fun, Extrinsic Motivation for Students, Teacher vs Judge, Problems with Pacing, and Quality of Teachers — we'll explore some of the many options for combining different methods of teaching-and-evaluating in Hybrid Labs`.

 

Should we evaluate student performance during discussions?  I encourage teachers to carefully consider the pros & cons (the reasons to say yes, no, or maybe not) and decide.  After doing this, I almost always avoid evaluation during discussions, and the sections below assume that discussions are not being evaluated.

 

More Learning and More Fun

In lab, usually discussions between students & teacher will help students learn more and have more fun.  Why?  Learning is better because formative feedback is usually much better with discussions than in written reports.  And interactive discussions are more fun, for a variety of reasons that are both intellectual and social.

 

Student Motivation from Lab Grades

The extrinsic motivation of working for a grade, which is an important part of the total motivation for most students, is missing in a discussion-only lab where — if discussions are graded pass/fail (so students get full points for participation) and if all students have participated in each planned discussion-activity during a lab — all student get the same grade.  Although students also will study for other reasons — because total motivation includes rewards that are extrinsic plus intrinsic, personal, and interpersonal — the desire to get a high lab grade will motivate most students.

David Perkins (1 2) proposes that "people learn much of what they have a reasonable opportunity and motivation to learn," and lab grades provide extrinsic motivation.  This motivational factor is a reason to supplement discussions with accountability — in lab reports and/or post-lab exam questions about ideas-and-skills from lab — to give students more responsibility and “ownership” of their work, in a hybrid lab.

 

Also, if "all student get the same grade" this can be a practical problem in courses where the instructor has decided – usually for motivational reasons – to give lab grades a medium-to-heavy weighting in the “total points” used for assigning course grades.    { some of my thoughts about Weighting of Lab Grades }

 

Teacher versus Judge — Is there a tension?

In well-designed lab education, the roles of teacher and judge should be mutually supportive, as when lab grades provide extrinsic motivation leading to effort and learning.

But when combining lab discussions with lab reports, tensions occur.  When I'm teaching labs, one benefit of discussions is the immediate detailed feedback I can give students.  This is easier in discussion-only labs when there is no grading, because I can focus my full attention on teaching (rather than judging) and students can focus on learning (rather than being judged).  Because I am only a teacher (and not also a judge) I can ask and answer any question freely, thinking only about what is best for helping students learn.  When I decide to withhold information — for example, by asking a question instead of giving a direct answer — my only motivation is pedagogical, and the purpose is to challenge students with an inquiry mini-activity (and adjust its difficulty) for the purpose of making them think, to let them play a more active role in their own learning.  I never have to worry about whether I am being unfair by giving too much information to one group (but not others) about a question that later will be used to assign a grade on their lab report.*  This is a liberating experience for me, and is educationally beneficial for my students.  And if discussions are not graded, students feel similarly free because they can ask any questions they want without fear that they will get a lower grade because their questions show a lack of understanding.

* For example, if I see Joe and Sue (working as lab partners) writing a lab-report response in a wrong way, should I provide coaching – with questions, hints, and explanations – that will help them understand what they were doing wrong and how to do it better?  Or should I remain silent and let them continue doing it wrong, so I can take points off on their report?  As a judge, silence is appealing because it's more fair to students who did not get a personal warning that would have prevented them from getting it wrong, or who figured it out on their own without help.  But for Sue and Joe the result of silence is that they won't get feedback until later (when they see points lost on their lab report, with minimal written “explanations for why” from me) and by this time their teachable moment is far in the past, and they probably won't think much about the experience or learn from it.  My instincts as a teacher are to teach NOW, during the lab while they're thinking, deciding, and doing, but if I'm also a judge this is more difficult and my effectiveness as a teacher is diminished.

This section has described an indirect tension between discussing and grading a written lab report.  There also can be direct tensions ==== [I.O.U. - Later, I'll finish this paragraph.]

 

Problems with Pacing

A lab with scheduled discussions has an imbalance of supply-and-demand due to unequal numbers, because there is one teacher and many students.  Although this problem cannot be eliminated, it can be reduced by using these strategies:

fewer groups for discussions:  The numerical imbalance can be reduced by asking students to organize themselves into larger groups.  For example,... {details}

better skills:  Teachers can improve their skill in leading discussions, to use time more efficiently so all discussions will fit into a lab session.

productive waiting:  When students must wait for the teacher to finish discussions with other students, they can... {details}

improved timings:  We can design each lab so discussions are evenly spaced throughout it (not delayed until near the end) and productive activities are always available.

fewer topics for discussion:  We can design hybrid labs that combine discussions (for some questions) with a written report (for other questions).  This reduces the number of discussions, and adds another productive activity – writing the report – that students can do while waiting.  The quality of the remaining planned discussions may increase because the pacing can be more leisurely.  Teachers also will have more time to interact with students informally in unplanned discussions that occur while walking around the lab-room to check on labwork progress and respond to student-initiated questions.

 

Quality of Teachers

In a lab where discussions are emphasized, the learning experience of students depends on interactions with their teacher, so...

What happens if students get a teacher with less ability, experience, or motivation?  This question is especially important for a large college course with many labs, taught by many graduate students who have a wide range of experience & abilities.

 

Quality of Teachers:  Teaching Scientific Method in Science Labs looks at my own experiences` with “working the room” during lab;  four types of teachers;  preparing teachers to be skilled discussion leaders;  and uniformity among teachers.

Uniformity among Teachers:  Whether in leading discussions or grading reports, we cannot achieve total uniformity so (as explained in My Philosophy of Lab Education) I think:  we should try to achieve quality with a “greatest good for the greatest number of students,” not an impossible uniformity in teaching & grading;*  instead of a mandatory rubric-system for grading, we should give TAs non-compulsory guidelines and recommendations;**  and regarding Justice in Grading, "almost always the best way to get approximate uniformity and justice is to normalize lab grades... [after explaining to TAs & students] what normalizing is, why (because it's the most fair way to grade) it will be used, and [because options-for-normalizing exist] how it will be done."

* Even if all graders use the same rubric-system, this will not produce uniform grading because each grader must decide how to assign a number for each report in every category.  These decisions will produce differing results, with some graders assigning higher points, and some lower.  Or, if each TA is responsible for achieving a specific average, the normalizing is not avoided, it's just shifted to individual TAs, with an extra constraint that is a time-wasting burden for them.  But when normalizing is used the focus of grading becomes quality instead of uniformity.  Each TA is free to grade the way they want, with their focus on quality, deciding how to assign relative grades “on a curve” within their own sections, because normalizing will compensate for differences between TAs.

** Experienced graders can describe the grading strategies they have developed that let them enjoy lab-grading the most (or dislike it the least) because these strategies let them grade well in a reasonable time with a feeling of justice, to produce a higher ratio of “personal satisfaction / time invested”.

 

A Wider Range of Ideas about Lab Education

My Philosophy of Lab Education covers a variety of topics:  Uniformity among Teachers` (is it possible? desirable? what should be our goals, and why?  can we achieve Justice in Grading with a compulsory rubric? by normalizing?) as described above, plus Educational Collaborations (with instructors, TAs, other lab directors,...) and My Personal History with Lab Education and more.

In a multi-TA course, if "all student get the same grade" this is a problem if the instructor has decided (usually for motivational reasons) to give lab grades a significant weighting when assigning course grades.    { my views on Weighting of Lab Grades }

 


 

Hybrid Labs — Combining Benefits

This section reviews the benefits & drawbacks of discussion-only labs (with no written reports) and reports-only labs (with no scheduled discussions).  Then it explains the advantages of hybrid labs that combine discussions with reports in a “best of both” designing of instruction.

 

Labs with only Oral Discussions

The previous set of sections` describes pros & cons of labs with only discussions.  Here is a summary.

pros:  Students often have More Fun & More Learning due to better formative feedback;  and tensions of Teacher versus Judge are reduced.

cons:  Without the personal accountability of graded reports, valuable extrinsic motivation is decreased; and too many discussions during a lab period can cause problems with pacing.

* Although it can be done, should we grade discussions?

Another factor to consider is the quality of teachers and related questions about uniformity & justice.

 

Labs with only Written Reports

pro:  When students report their thoughts in writing (by "answering questions, showing data, doing calculations, solving mini-problems,...") this can be a valuable thinking activity that leads to learning, if the assigned responses (what we ask them to write) are well designed.

con:  With graded reports, students get a lower quality of formative feedback — because it has less detail and is delayed — compared with discussions in lab.  Of course, asking students to write reports does not mean “no discussions are allowed” is the lab policy, and improvised conversations still occur, especially those begun by students, and anything related to lab safety.  But when discussions are not scheduled during a lab, they are less likely to occur, and are less likely to have significant ideas-and-skills content.

con:  The grading itself also limits freedom of discussion because when an idea will be graded in a report, a teacher who wants to be fair will not discuss this idea with some students but not others.  This effort to be fair can reduce teaching effectiveness, in a conflict of teaching versus judging.

 

We can think about pros & cons for students (above) and also for teachers.

con:  In a feeling that I think is shared by most teachers, I usually don't enjoy grading lab reports because it requires a lot of time, and produces only a small amount of satisfaction, so it has an extremely low ratio of satisfaction/time.   For me, the level of satisfaction is usually low for two reasons:  mainly it's because my efforts are not very effective in helping students learn ideas & skills, due to the minimal-and-delayed formative feedback;  also, grading reports requires a lot of time to make a small difference in a student's course grade, compared with quick-and-easy grading decisions about points on quizzes and exams;  and usually a quiz or exam has a much higher “spread between students” (e.g. as measured by standard deviation) than with a lab report.   But the grading experience can improve if we...

 

Design for Grading:  When teachers grade lab reports, their ratio of “personal satisfaction / time invested” can be increased by designing reports for grading that is quicker-and-easier.  How?  We can make grading more efficient by carefully choosing the content & format of student responses (what we ask them to write & how), and make reports shorter (perhaps combined with reducing the weighting of lab-grades when determining a course-grade) by moving some responses from reports into discussions and post-lab testing, as explained below.

 

Hybrid Labs — with Discussions + Reports, and More

 

Moving Responses between Discussions & Reports

A simple way to partially solve these problems in a pure lab (with only discussions, or only reports) is to convert a pure lab into a hybrid lab, either by moving some activities from discussions into a report (to improve extrinsic motivation, and decrease problems of pacing) or, in a reverse action, by moving some activities from a report into discussions (to improve formative feedback, and reduce tensions between teaching & judging).

converting from only-reports to hybrid:  When an idea will be graded in a report, so a teacher does not want to "discuss this idea with some students but not others," some aspects of the idea can be included in a scheduled discussion, so all students will have the same information.  This discussion — which can be part of a teaching strategy to adjust the level of difficulty — improves the formative feedback and decreases teacher-vs-judge tensions.  Or, for some questions a teacher might adopt a policy of giving feedback during lab with a thumbs up (ok as-is) or thumbs down (not ok) or sideways (partially ok), and then let students revise their answer, either with or without hints from the teacher about how to revise.  Or an idea can be totally removed from a report, so it's only discussed.

converting from only-discussions to hybrid:  Some ideas can be moved (partially or totally) from discussions into a report, to increase extrinsic motivation and improve pacing.

You also can move activities, one way or the other, to “shift the balance” in a hybrid lab that already is part-discussions and part-reports.

 

Educational Design includes Evaluation Activities

This page begins with a process of goal-directed design in which we define educational goals (for ideas-and-skills, plus motivations & attitudes) that will guide us in designing instruction with useful learning activities and teaching strategies.  When instruction is designed effectively there will be mutual support between goals (for what students should learn) and motivations (so students want to learn) and activities (offering opportunities to learn) which include evaluation activities that reliably-and-accurately measure appropriate knowledge by testing ideas-and-skills that are the educational goals, and (in well designed instruction) have been the focus of teaching and learning.

 

Options for Grading Labs

Lab Grades:  In labs, ideas-and-skills can be evaluated in many ways:  by a grading of reports, or discussions (but should we?), and pre-lab quizzes, and with post-lab testing (*) by putting lab-related questions on regular tests (in a small quiz or big exam), or in special lab-tests with responses that are written or oral.  Some labs can include built-in accountability for work that is qualitative (identifying an unknown chemical,...) or quantitative (determining the concentration of a solution,...), with students getting more points for coming closer to the correct answer.

Course Grades:  Teachers can combine some of these grading-inputs, or all, to determine a lab grade.  In a lab course, the lab grade is the course grade.  In the more frequent non-lab courses, lab grades are only one factor (among many) in determining an overall course grade, so we ask how much should lab grades be weighted?

 

* Using post-lab testing (of what is being learned in lab) will motivate students to view discussions & reports as opportunities to learn ideas-and-skills that later will be tested.

But ... it's difficult to write exams (for labs or in general) to test higher-level thinking skills.

 

 
APPENDIX

 

Designing a Discussion-Based Lab

Split a lab into parts, define a Discussion Activity for each part, make a grid, and during lab you mark it (X) when groups finish activities:

 
Discussion Activities
 Students 
 Part 1 
 Part 2 
 Part 3 
 Part 4 
 Group A 
X
X
 
 
 Group B 
X
X
 
 
 Group C 
X
X
X
 
 Group D 
X
X
 
 
 Group E 
X
 
 
 

 

Activities for Thinking-and-Learning

In a lab-based Activity for Thinking-and-Learning, students can learn from Explanations, by Discovery, and during Activities.

Thinking Skills in Chemistry Labs has examples of "thinking activities [i.e. learning activities] in general chemistry labs that help students learn observation-based inferences, hypothetico-deductive logic, mathematical data analysis, experimental design, the logical-and-social process of science, and more."

 

The Problem of Pacing  (details)

Here are details about two strategies to reduce the problem of pacing`.

• fewer groups for discussions:  ... For example, if students are doing labwork in pairs, at some point during a lab they go to a student discussion area and begin to discuss a scheduled topic;  after 3 or 4 pairs are in this students-only discussion, they either arrive at a consensus (by persuasion if necessary) or an understanding of their disagreements.  Then they have a students-and-teacher discussion.  By using this method, in a 22-student class instead of 22 discussions (with individuals) or 11 (with pairs) there can be 3 discussions, each with approximately 6-8 students.

Of course, flexibility is possible.  Due to differences in labwork timings for when students reach a "point during the lab" when they're ready to begin discussions, instead of each supergroup having 6-8 students the splits might be 4-12-6.   Or differences in group size can be planned;  in a lab with five questions (A B C D E), perhaps A is discussed with all 22 students, B, D, and E in groups of 6-8 students, and C separately with each of the 11 pairs.   And plans can be changed;  if you're running out of time in a lab session, some discussions (C, D, or E) can be done with larger groups, maybe with the whole class.

 

• productive waiting:  ... Students can prepare for (and maybe start doing) the next part of their labwork, or talk (about the lab, or their next exam, or other things in life) which helps build student-student relationships and community.  It will be useful to explain the numerical supply-demand situation, and apologize for the inconvenience, but suggest ways for students to use the waiting time productively.  When doing this, I use the analogy of waiting for a physician;  you know that usually you'll have to wait, so it's best to just accept this and decide to use the time productively.  Often, most students will have a good attitude about waiting.  But sometimes some students may become visibly impatient because they want to leave the lab (this is permitted in college but not K-12) ASAP so they can use their time any way they want, and their attitude can affect other students;  it may be worthwhile to have a private conversation with these students.

 

My Experiences with Discussion-Based Labs

In 1991, I discovered that planned discussions can make personal interactions easier.  I enjoy conversation, especially talking about ideas.  But if there is no specific reason to talk with students in lab, so everything depends on my social intuitions and skills in “working the room,” sometimes it's difficult to smoothly begin & end conversations, and to find a good balance between ignoring students and bothering them with too much attention.  But these interactions were easier when conversations were scheduled throughout the lab, in planned discussions with topics that were interesting and educational.

In 2012, I was reminded about the benefits of extrinsic motivation that comes from grading reports.  But for a variety of reasons — especially to minimize teacher versus judge tensions, and maximize the high-quality formative feedback of discussions — we should explore the benefits of combining ungraded planned discussions with graded reports in hybrid labs.

 

Subjective Evaluation of Discussions

Converting discussions into miniature oral exams — by evaluating the quantity and quality of each student's contributions during discussions — is one option for evaluation.

After carefully considering the factors described below, in my own teaching I usually avoid evaluation during discussions.  For your teaching, you can weigh the pros & cons of grading discussions (yes, no, maybe not,...) and decide for yourself.

 

A reason to say “yes” is because grading of discussions provides extrinsic motivation for students to impress the teacher (so they can get a high grade) by investing more effort in preparing for discussions and then participating more actively, and both of these results will help them learn.

But a reason to say “no” is because judging discussions may decrease the "liberating experience" of teaching without judging.  During a graded discussion a teacher may be distracted from teaching if they also must be thinking about how many points to give each student.  And students may not feel free to ask any questions they want, without fear, if they are worried that their grade might be lowered if their responses or questions show a lack of understanding.

Another reason for “maybe not” is the difficulty of reliable accuracy in grading a group discussion.  A high-quality oral exam is an excellent opportunity for a teacher to discover the depth of what a student knows, and how well they can think with what they know, especially with exams for individuals. (oral exams: pros & cons)   But in a group setting, making accurate evaluations for every student is more difficult due to social interactions.*  And, returning to the "no" above, it can be difficult — especially when labs are taught by multiple TAs and some have a lower level of skill — to avoid an information overload caused by the requirement to be both teacher and judge, to teach effectively while also assigning an accurate grade for every student.  Also, problems with pacing will be amplified because a teacher will want to allow enough time for each student to show what they know (so they can be judged), instead of just being satisfied (as a teacher) if someone, either student or teacher, talks about the most important ideas.

* In a group discussion, some students can appear to know more than others (even when they don't) if they talk more frequently, and with more confidence, due to their personality and their skills in the art of discussion.  Although discussion skills are valuable in most areas of life, including science, a teacher who wants to evaluate other ideas-and-skills will have to consider the students' differences in discussion skills, and make adjustments in grading.

 

Special Oral Exams:  One option is to have most discussions un-graded, but to occasionally schedule discussions (individually or in a group) that will be graded as oral exams, when students know they will be graded.

 

Other Types of Lab Performance:  In addition to a subjective grading of lab discussions, we also can do a similar grading of student performance in other activities — including lab techniques, ability to follow directions in a lab manual, or to cope with inquiry challenges that require improvising — and assign a grade-number for each student for every type of performance, or for their overall performance.  As with discussions, these other skills can be graded frequently or occasionally, in the context of regular labwork or in special testing situations.