Implementing Classroom Demonstrations – Incorporating Student Inquiry

Amy Chan-Hilton (@abchan123) of Florida State University explains exactly what to do with all the other posts. That is, how do you actually get educational value out of running in class demonstrations.

With the start of a new academic year, I find myself with renewed enthusiasm to try something different or tweak an activity done previously in my courses.  Nigel’s Teaching Fluid Mechanics blog provides wonderful examples of classroom demonstrations that can be implemented in class.  Another resource is the book H2Oh! Classroom Demonstrations for Water Concepts (ASCE, 2012) (full disclosure: I served as editor, along with Roseanna Neupauer, of this publication).

I am motivated to incorporate demonstrations and other active learning* activities in my engineering courses for several reasons.  First and foremost, I want to improve my students’ learning.  Why bother showing up to class if what happens during the class period does not add to my students’ learning and motivation?  This is easier said than done (see below for a little more on this).  I also aim to keep my students engaged during the class period.  My class occurs right after lunch; so keeping my students awake is key, as sleeping students will not learn much (if at all!).  The third reason is selfish on my part – to have fun during class.  I would bore myself and be very tired if I were to lecture for the full 75 minutes each class.  If I cannot hold my own attention during class, how can I expect my students to do so?

*There are plenty of resources defining active learning, describing effective examples of active learning, and studies of its impacts on student learning and attitudes.  A recent PNAS article by Freeman et al. (2014) and highlighted in Wired points to evidence on the positive impacts of active learning on student success in STEM courses.  In addition, a recent post by Lisa Benson on the Teaching Fluid Mechanics blog nicely highlights examples of active learning activities and offers best practices for implementing them.

Now back to in-class demonstrations.  Whether you develop your own demo, use and/or adapt established ones (such as those described in the Teaching Fluid Mechanics blog, the H2Oh! book, and/or others), one needs to consider implementation.  At what point in the class period will I conduct the demonstration?  How long will the demo really take? (I have had my share of experiences when I miscalculated time and had to rush through a demo because the class period was ending.)  What will my students be doing during this demo?  What do I want my students to get out of the demo – entertainment, stimulate interest, test theory or hypotheses, apply knowledge?

The last point is the most important when planning the implementation of a demo.  Certainly demos can be used to hold student interest, but this alone will not make significant impact on enhancing student learning.  Studies by Crouch et al. (2004) and Zimrot and Ashkenazi (2007) showed that students who engaged in the demos through inquiry learned more than students who passively observed classroom demonstrations.  When student-centered learning and inquiry-based learning techniques were used, in which students make predictions about the demo, observe the outcome, and discuss with their peers and the instructor, these implementations of the demos not only resulted in student learning gains but also helped to overcome student misconceptions.  So while it is important to practice a demo before class to check that it works, careful consideration of the student inquiry and interactive aspects during the demo helps us achieve the goal of improved student learning while both students and instructors can also have fun during the process.

Here’s a simple example of how intentional student inquiry and engagement can be incorporated into the implementation of the pipe networks and head loss demo posted in the Teaching Fluid Mechanics blog, in which the time to fill up an equal volume of water for two different lengths of tubes from the same water tank are compared.

  1. The tank and tubes are prepared and shown to the students.
  2. Ask the class what is different between the two tubes (you can randomly ask 2-3 students for their observations). Once the students have determined that the lengths are different, then have a student come up to measure the lengths of the two tubes).
  3. Tell students that each tube will be used to fill up a cup. Will there be a difference in the time it takes to fill each cup with the same volume?  If different, which one will fill up faster?  Why?  Students can pair up to discuss this using Think-Pair-Share or other techniques (this can take 3-5 minutes).
  4. Run the demo, have 2 students record the times to fill up the 2 cups.
  5. Have the students in pairs compare their predictions to their observations and data from the demo. Ask the class what the data from the demo shows (again randomly asking 2-3 students).  Then this can lead to a more in-depth discussion in which the instructor uses students’ comments and questions to guide the class into particular points, or you pose additional guiding questions (prepared ahead of time).
  6. Students in pairs can continue with the quantitative analysis of the demo.

Happy teaching!

Amy B. Chan Hilton

Associate Professor, Civil and Environmental Engineering

Florida State University,


Bhatia, A. (2014). “Active Learning Leads to Higher Grades and Fewer Failing Students in Science, Math, and Engineering.” Wired.  Accessed on 8.12.14 at

Chan Hilton, A.B. and Neupauer, R.M. (eds.) (2012). H2Oh!  Classroom Demonstrations for Water Concepts, American Society of Civil Engineers, Reston, VA.

Crouch, C.H., Fagen, A.P., Callan, J.P., and Mazur, E. (2004). “Classroom demonstrations: Learning tools or entertainment?” American Journal of Physics, 72, 835-838. DOI: 10.1119/1.1707018

Freeman, S. et al. (2014). “Active learning increases student performance in science, engineering, and mathematics.” Proceedings of the National Academy of Sciences, 111(23), 8410-8415. doi: 10.1073/pnas.1319030111

Zimrot, R. and Ashkenazi, G. (2007). “Interactive lecture demonstrations: A tool for exploring and enhancing conceptual change.” Chemistry Education Research and Practice, 8(2), 197-211.  DOI: 10.1039/B6RP90030E

An index of all the demonstrations posted on this blog can be found here. Don’t forget to follow @nbkaye on twitter for updates to this blog. If you have a demonstration that you use in class that you would like to share on this blog please email me ( I also welcome comments (through the comments section or via email) on improving the demonstrations.


Active Learning – What, Why and How

Lisa Benson, Associate Professor, Engineering and Science Education

“Don’t lecture, teach!”

I was talking recently with a post-doc who is trying to figure out if he wants a career in industry or academe. He thinks he would prefer academe. “I love my research. I love mentoring students. But,” he adds, “I hate lecturing.” As someone who embraces active learning and promotes it among colleagues near and far, I did a double take. I blurted back, “Well, just don’t lecture.” He thought I meant that he should refuse to teach. “No, no – I mean don’t lecture, teach!”

Our conversation reminded me of how little grad students, post-docs and even some faculty know about different ways of engaging students in the classroom and about different approaches to teaching besides lecturing. But the effort put into teaching is not often recognized or rewarded, at least not at the same level as effort in the research lab. Is it worth it?

A recent meta-analysis of over 150 research studies on active learning indicates that there are indeed positive outcomes from active learning that make it worth the effort of going beyond lecturing in the classroom1. Authors  Freeman, Eddy, McDonough, Smith, Okoroafor, Jordt and Wenderoth from the Department of Biology at the University of Washington analyzed outcomes of studies comparing student performance data on exams and concept inventories in science, technology, engineering and mathematics (STEM) courses that were primarily lecture format versus those employing active learning techniques. Accounting for variations in study methodologies, “publication bias” (the tendency to not publish results with small effect sizes), student quality and instructor identity, the analysis revealed that students in active learning classes scored higher on course exams and even higher on concept inventories than their peers in traditional lecture-based classes. Students in lecture-based classes were 1.5 more likely to fail than those in active learning classes. Although the effects were more pronounced in small classes (n ≤ 50), they were consistent across all class sizes, as well as across all STEM disciplines.

Empirical evidence is powerful stuff, but in spite of these new findings, many instructors still resist the idea of changing the way they teach. Maybe some small steps are in order rather than giant leaps. Active learning doesn’t have to turn a class inside out; but it can effectively take that love of research and love of mentoring that my colleague enthusiastically identified with and transfer it to the classroom.

What is active learning?  Any activity that engages students beyond just listening is technically active learning. When we lecture, we are basically telling students what they need to know. But students remember far more of what they say and do than of what they hear and see. Sometimes you have to lecture, but even lecturing can be broken up by short activities that help students learn more effectively.

What are the benefits of active learning?

  • Improved attendance – class is now something different and is attending is more worthwhile
  • Deeper questioning – students get to practice answering and generating questions
  • Higher grades and lower failing rates – research is providing evidence of this!1

How do I implement active learning?

  • Explain what you are doing and why up front; get student buy-in. This limits complaints from students that you are not actually teaching.
  • For paired or group activities, have the students form into groups of 2 – 4 where they are sitting. This saves time in regrouping, and gives students a sense of control over the activity.
  • Assign roles; most often groups need a recorder to capture ideas, but occasionally different roles might be appropriate (timekeeper, monitor, technician)
  • Explain the task, and this can typically be done orally. For more complicated problems or activities, a slide, handout or steps written on the board would be helpful.
  • Call on individuals randomly, both while working and when the activity ends. This is an important step to keep students accountable.
  • Keep activities short to keep students from wandering off task and to reduce frustration for groups that are struggling.
  • Always circulate around the room to listen in, give hints, and check for understanding.
  • Vary the activities you do with students rather than rely on the same in-class activity or format. Use different structures (pairs, groups, reflections, etc.) to keep the class interesting.

How do I find the time to fit in active learning and still cover everything?!  Our job as educators isn’t to cover material, it is to uncover it! You can’t afford not to engage students to help them learn.

  • Reduce the time needed for note-taking. Free up time by putting some of your class material on handouts, leaving gaps and inserting questions.
  • Reduce the time needed for lecturing. Record some of your lectures online and assign viewing it outside of class (aka “flipped classroom”). Follow up with directed questions or applying concepts in a problem during an activity.
  • Assign readings or post videos to be viewed online to introduce the topic you are teaching. Follow up with directed questions or applying concepts in a problem during an activity.

Some examples of active learning methods2:

  • In-class teams: Form teams of 2 – 4 students, and choose team recorders. Give teams 30 seconds – 3 minutes to do reflect on course material:
    • Recall prior material or a previous lecture
    • Answer or generate a question
    • Start a problem solution
    • Work out the next step in a derivation
    • Think of an example or application
    • Explain a concept
    • Figure out why a given result may be wrong
    • Summarize a lecture

Collect responses by randomly calling on team recorders. Some instructors call on people in the back of the room first to bring them into the discussion.

  • Think-Pair-Share: Pose questions for students to think about individually. (See question starters below.) Have students form pairs that first produce joint answers and then share them with the class. Pairs may discuss answers with other pairs before sharing.
    • How does ___ relate to what I’ve learned before?
    • What conclusions can I draw about ___?
    • What are the strengths and weaknesses of ___?
    • What is the main idea about ___?
    • What is the best ___ and why?
    • What if …?
    • Explain why…
    • How are ___ and ___ similar?
    • Why is ___ important?
    • How would I use ___ to …?
    • How does ___ affect …?
  • Cooperative Note-Taking Pairs 3: Students form pairs to work together during the class period. After a short lecture segment, one partner summarizes his or her notes to the other. The other partner adds information or corrects. The goal is for everyone to improve his or her notes. This takes about 2 minutes and can be repeated 2 – 3 times during a class period.
  • Guided Reciprocal Peer Questioning4: Students work in groups of 3 or 4 and are provided with a set of generic question starters. (See question starter list above.) Each student individually prepares 2 or 3 thought-provoking questions about the course material from lecture or a reading. Questions are discussed in small groups at the beginning of class, and the whole class then discusses questions that were especially interesting or controversial in the group discussions.
  • Paired Programming: Two students actively collaborate on a computer-related task. One is the pilot, who does the keyboarding, and the other is the navigator, who identifies problems and thinks strategically. The two switch roles frequently.
  • TAPPS: Thinking Aloud Paired Problem Solving: Similar to paired programming, students form pairs, with one being the problem solver/explainer, and one being the listener/questioner.
    • The instructor defines the activity or problem
    • The problem solver talks through the first part of the solution or derivation.
    • The listener questions, gives hints where needed, and keeps the problem solver talking.
    • After several minutes the instructor stops the activity, collects solutions from several listeners to make sure everyone in class understands up to that point.
    • Pairs reverse roles and continue.

This can be used 7 – 8 minutes at a time, followed by a review of the problem solution with the whole class. Or it can be used for a complex problem that takes the whole class period to work through, with roles being reversed periodically.

  • Minute Paper5: End the lecture or lesson about two minutes before the end of the class period. Ask students to anonymously write down on index cards or a half-sheet of paper:
    • Main points
    • Muddiest (least clear) points

Collect the papers and use responses as “formative assessment” – in other words, use it to inform your own teaching practice. Determine what students do and do not understand, and adjust your next lecture/lesson or even online support materials to address common questions. You can also provide students the option of including their names so you can address individual questions via email or during office hours.



1 Freeman, Scott; Eddy, Sarah L.; McDonough, Miles; Smith, Michelle K.; Okoroafor, Nnadozie; Jordt, Hannah; and Wenderoth, Mary Pat. 2014. Active learning increases student performance in science, engineering and mathematics. Proceedings of the National Academy of Science, published ahead of print May 12, 2014, doi:10.1073/pnas.1319030111

2National Effective Teaching Institute Workshop Handout

3 Johnson, D. W., Johnson, R. T., and Smith, K. A. 1998. Active learning: Cooperation in the college classroom (2nd ed.) Edina, MN: Interaction Book Co.

4 King, A. 1993. From sage on the stage to guide on the side. College Teaching, 41(1), 30-35.

5 Angelo, T. A. and Cross, K. P. 1993. Classroom Assessment Techniques: A handbook for college teaching (2nd ed.), San Francisco: Jossey-Bass.

Videos of “Momentum – air jets and paper plates”

Here are some video of the “Momentum – air jets and paper plates” demonstration. The full videos are linked from the GIF titles

Jet impinging on a plate


Jet impinging on a cup


An index of all the demonstrations posted on this blog can be found here. Don’t forget to follow @nbkaye on twitter for updates to this blog. If you have a demonstration that you use in class that you would like to share on this blog please email me ( I also welcome comments (through the comments section or via email) on improving the demonstrations.

Momentum – air jets and paper plates

So many momentum examples in fluids text books revolve around air or water jets striking various plates, vanes, and cups. The calculations are quite easy and a good reminder that momentum is a vector so sign and direction mater. Here is an easy to build demonstration that allows you to illustrate this point.


  1. Long thin (somewhat flexible) wooden rod
  2. Duct tape
  3. Plastic or paper cup
  4. Plastic or paper plate
  5. Compressed air can (like those used for cleaning keyboards)
  6. Student volunteer

Cut out the flat section of the paper plate and cut the base of the cup out so that it is about 5-7 cm deep. Tape the cup base and plate to either end of the rod.

Photo Jul 07, 9 37 59 AM


  1. Hold the rod in the middle with the flat plate up.
  2. Spray the compressed air jet at the center of the plate, normal to the surface, from a distance of 5-7 cm. The plate should deflect back (it will also likely twist which is unfortunate)
  3. Flip the rod so that the cup is at the top.
  4. Spray the compressed air again and observe the (hopefully greater) deflection.


The analysis can be done quantitatively though the result can only be qualitatively compared. We treat the air jet as a momentum conserving flow until impingement. For the flat plate the jet is deflected radially in all directions and, other than a small component due to the plate twisting, there is no outflow momentum component parallel to the initial air jet direction. See the control volume diagram below.


The control volume version of the momentum equation is written as


where the positive x direction is to the right. For the cup, some of the jet momentum is deflected in the opposite direction to the incoming air jet and the control volume diagram looks like this


The resulting control volume momentum equation is written as

ΣFx=Rcup=ρQ(Uout cos θ -(-Uj))

As such

Rcup> Rplate.

Therefor, the rod should deflect further when the air jet impinges on the cup compared to when it impinges on the plate.

An index of all the demonstrations posted on this blog can be found here. Don’t forget to follow @nbkaye on twitter for updates to this blog. If you have a demonstration that you use in class that you would like to share on this blog please email me ( I also welcome comments (through the comments section or via email) on improving the demonstrations.