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Strategies For More Effective Labs Chemistry

Too often we have students who float through lab exercises without making connections to the science content they are learning in class. Some students struggle to find meaning of the lab and just run through the motions, copying other student’s data and ideas, and then handing in the lab report without a second thought about the science they just witnessed. Many students feel lab time is just for fun and not for learning at all. As teachers, we know the lab was intended to challenge students, make students discover answers to phenomenon, and reinforce the subjects we teach in class. So why is there such a large disconnect between labs and classroom content? The execution of the labs is an essential skill which teachers need to refine over time in order to make their labs more valuable to their students. These are a few tips that teachers can use to help drive labs towards that ultimate goal.

  1. Flip Your Pre-Lab: Regardless if you are a novice or an expert in flipping, flipping your pre-lab isn’t a difficult process and can prove to be very beneficial. You can create a video just by videotaping yourself in the lab with your cellphone! I prefer to screencast my computer using screencast-o-matic and voice over a PowerPoint that contains ideas and images from my lab. I upload my videos to an online website known as EDpuzzle, which is a free website you can use to track students watching your videos (and embed questions during the video to assess the students’ understanding). Both of these sites are free and very easy to use. Other teachers upload to their personal websites or YouTube. A flipped pre-lab could include reviewing safety rules pertaining to the lab, showing how to use equipment, and practicing necessary calculations. If the students complete this pre-lab at home, they come into class ready to work, increasing the time spent on the actual wet lab. The flipped pre-lab can decrease lab misconceptions and give the students a better understanding of their goal before they start the lab. In addition, flipping the pre-lab is helpful for inquiry style labs because the students will already know how to use the equipment and account for safety issue that may arise.
  2. Class Lab Discussion for Inquiry Labs: Inquiry labs can be daunting and cumbersome. One strategy to make these labs more manageable is to have a class discussion before the lab starts. Give the students a larger, overarching problem that needs to be solved. In pairs or small groups the students should come up with variables that they can test to solve the problem. A simple example could be “What factors affect the rate of a reaction?” Students can come up with factors such as temperature, surface area, and more. Next, have a class discussion and record all of the student’s variables down on the board. In some labs, it may be overwhelming for one lab group to test all of the variables that were brainstormed. Therefore, assign each lab group one variable to test from the list. At the end of the lab, students can exchange data to solve the overall problem. For example, group one can study temperature effects and group two can measure surface area affects. If there are not a lot of variables, double up the lab groups and they can compare their answers at the end of the lab. The individual lab groups will have to brainstorm constants for their lab and come up with a plan of action. Once the teacher checks the plan and constants, the group can get started on a series of trials to test their assigned variable. In most cases, the students should have a pre-planned data table and a graph to show the relationship that they tested. At the end of the lab, each group should report about the variable they tested, constants they used, and their results to the class in a short, two minute presentation. The class should record that data to create a class master set of data that shows all variables and their effects. This method will reinforce the need for multiple trials of the same variable in an experiment, while not putting too much pressure on any one group to solve the overarching problem in a lab because the lab groups are focused on one part of the overall problem. Together as a class, they can understand the problem as a whole and witness how a group of people can work together to solve the larger problem.
  3. Lab Quizzes: In my classroom, like many others, most labs are done as a small group or pair of students. Some teachers assign roles to each student to hold them accountable for participating in the lab. Despite the effort it takes to arrange the lab and possibly assign roles, some students can still do the bare minimum and copy other students’ work. To really tie the lab in with the classroom content and ensure that every student has motivation to understand the lab, lab quizzes can be given periodically to test student understanding. The quizzes can be short, using sample data from the lab or questions that may show up on future tests. Some quizzes may have the same questions that were in the lab, but with new numbers. Other quizzes might have questions about error analysis from a lab. You can also create a mini lab practical to ensure the students have proficient lab skills. In AP classes, I often give one AP question from an old exam that relates to the lab we completed. Lab quizzes should be given soon after the lab is complete or at least by the end of the unit. The bottom line is if the students know they will be individually assessed on their lab, they will most likely put more effort into understanding the lab as it is being done. Unfortunately, many students don’t find value in work that is not graded. These individual quizzes that can take as little as five minutes can be the item that students find the most motivating factor to understanding the lab.
  4. Challenge Labs: I have changed some of my standard labs into challenge labs. Instead of having students confirm the formula of a hydrate (I am a chemistry teacher) or confirm the value of a constant, my teams compete to get the closest value to the correct answer. It doesn’t always change the makeup of the lab itself, but it adds a healthy competitive element to the lab that engages more students. Some labs did change, like my density lab. Instead of identifying if sample size affects the density of an object or confirming the makeup of a sample based on density, I gave teams a sample of aluminum metal that was pre-massed by me, and another sample of aluminum without a mass that had a different shape and size. Students could use any equipment other than a balance to find the mass of the second sample. The closer they got, they better they scored on the lab!

It is important to conduct meaningful labs in class. If the students cannot connect the content in the labs to the content in their homework, classwork, and exams the labs become a waste of time and energy. The labs need to be a driving force in the classroom and something to refer to when describing questions in class. I hope you consider trying one or more of these strategies for your labs to help connect your labs to your chemistry content.

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Evolution 3D Printing Hominids Fossils Phenomena

By Dan Williams  

Many of us are familiar with the famous quote from Theodosius Dobzhansky, that “nothing in Biology makes sense except in the light of evolution.”  I am not alone when I state that evolution is one of my favorite topics within Biology. Whether its examining derived traits within butterflies, predator prey relationships, or how a complex molecule like the ATP synthase evolved, the topics in evolution are varied, complex, and fascinating.  

Evolution however, is often the most misunderstood topic in Biology and despite our best intentions, we perpetuate the misconceptions with our classroom examples, exercises, and labs.  Please do not misunderstand me, I am not suggesting at all that I am any different –regardless of my best efforts, I too, unknowingly, have passed on misconceptions about evolution to my students.  Luckily, there are new tools to teach evolution which will inspire students with wonder, have them question phenomena, and help uncover and address the misconceptions we have built into our teaching of evolution.   

One such tool is the three dimensional printing of fossil scans.  It is easy to use, inexpensive, powerful and works well within a New York State Science Learning Standards (NYSSLS) environment.  Fossil scans are accurate 3D renderings made by paleontologists of real fossils within the field which can be freely downloaded from public databases for printing on common 3D printers.  At the conclusion of this article I have provided links to resources that can be used to download and 3D print fossils for your classroom.

3D Printed Fossil Crania (L-R H. Heidelbergensis, H. naledi, H. Neanderthalensis, H. Sapiens)

A few months back, I was beyond excited when I cleaned off my new fossil crania scan from the 3D printer.  It was of a new hominid that was in the news called Homo naledi.  My students were also excited, they asked lots of questions about naledi, its discovery and human evolution in general.  I decided to perform an impromptu experiment with my new fossil crania and some other 3D prints I had laying around. I placed before my students the unidentified crania of Homo sapiens, Homo neanderthalensis, Homo heidelbergensis, Homo erectus and the new naledi print.  I asked my students to place them in “evolutionary age order” –in other words, from the more primitive to the most advanced species.

Not surprisingly, my students placed the crania in order: small too large.  Intuitively, this made sense to them, however it was completely wrong. Homonaledi, the smallest crania, actually only dates to around 300,000 years ago –concurrent with Neanderthals and late Heidelbergensis –hardly the most ancient.  Evolution, we know is change, not progressive change, just change. My students “knew this.” We always talked about how extinction is evolution (bad change for the extinct), I even had slides showing that Neanderthal brains were larger than ours (implying they might have been more intelligent than us) but they died out and here we are.  I emphasize lots of examples of non-progressive change in my lessons. None of this mattered when my students were faced with objects they could touch, look at and observe. Obviously my “talking about evolution,” and “showing examples of evolution” was not enough to dispel the myth that evolution is progress.

Through self-reflection I realized that I had reinforced this misconception.  Whether it’s peppered moths in industrial England, the fastest cheetah catching the slowest gazelle, Hardy Weinberg with M&M’s or the beaks of finches, all of my hands on activities double down on the idea that evolution is progressive change.   

Here on the desk in front of me, however, was a phenomenon; hominid crania did not progressively get larger –what on earth was going on?

If student interest and excitement on a topic is measured in the quantity, quality, and decibel level of questions, this phenomenon was a home run!  I had to settle my students down, restore order, and respond to each question they had with questions of my own –they claimed their brains hurt after only a few enjoyable minutes.

This would be a great story if it ended there, but the 3D fossil scans provided so much more than a quick phenomenon to start teaching a unit.  We examined the fossils scans, visually observing the presence or absence of features and measuring differences between the crania with calipers.  Claims were made based on the observations, data charts, and graphs were created to examine the evidence of the crania. The reasoning of the students’ hypotheses were hotly contended between groups.

Students measuring 3D printed crania

I have now 3D printed fossil scans of mandibles, as well from all of the aforementioned species, plus Australopithecus afarensis and Australopithecus boisei.  These provide additional data to examine so that my students can make claims about diet and the processing of food. In some ways, the mandibles are easier than crania, as tooth diameter (buccolingual width) is a more consistent measurement for students to obtain and compare. 

Students made distant matrices of their data from the crania and the mandibles (separately).  They then sketched cladograms based on their claims of ancestral and derived traits. They have used an erectus 3D print to determine ancestral traits in crania and the boisei 3D print for ancestral traits in mandibles.  

While the discussions were valuable, the students found the cladograms difficult to generate by hand.  Most cladogram builders available today are for DNA comparisons, however I found an easy to use app developed David Dobson of Guilford College called “Simple Clade.”  It was invaluable in creating cladograms, manipulating for maximum parsimony for unbiased data analysis of the student claims. The cladograms however, did not stop the arguments that had now generated among the students.  The 3D prints provided phenomena that was not easy to explain, and fostered many claims on evolution that students actually wanted to explore. Best of all, none of the claims were based on evolution as progress.

Like most biology teachers, evolution is a major passion of mine, hominid evolution specifically.  I also find that hominids interest students as much (or almost as much) as dinosaurs. Using hominids as examples captivates students and provides ample phenomena to study.  I have read about human evolution for years, watched videos about it, examined anatomical diagrams, but until I held 3D prints of hominid skulls in my hands, I can honestly say I did not fully understand human evolution.  

The same can be said for my students, as well.  We discussed evolution, and I gave traditional examples of evolution, but until they held the 3D scans of fossils in their hands, they had misconceptions.  I never knew my traditional methods of teaching evolution led to misconceptions, working with 3D printed fossil scans not only helped uncover the students misconceptions, but also helped clear them up.

If you have any questions or are looking for the specific methods of how to download and 3D print your own fossil collection, please e-mail me at dan.williams@shelterisland.k12.ny.us

Useful Links

Fossil Databases:

African Fossils https://africanfossils.org/search

Morphosource https://www.morphosource.org/

Educational Links

iDigfossils http://www.idigfossils.org/

Human Evolution Teaching Materials Project https://www.hetmp.com/

Paleoanthropology

John Hawks YouTube Channel https://www.youtube.com/channel/UCVfaXPlLTPTjbU-ed9VMBfg

Programs Used

SimpleClade http://guilfordgeo.com/simpleclade/index.html

MeshLab http://www.meshlab.net/

MeshMixer http://www.meshmixer.com/

MakerBot https://www.makerbot.com/

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Cool Tools: Loopy

Systems thinking is as important as it is hard.  As we look at the New York State Science Learning Standards, we see a clear role for systems thinking.  Systems and System Processes is one of the Cross-Cutting Concepts, and Developing and Using Models is a Science Practice.  It should be obvious to all of us that where we are going as a state is very much to system-land.

There are many ways that we can model system dynamics.  Many of us model systems in our classrooms whenever we engage in “simulations”, or other types of modeling activities.  And I’m sure most readers are well aware of the various interactive computational simulations that have been created for students to work with.  But there are not a whole lot of computational resources that allow students to construct relatively robust models of systems for their own investigation.  This is mostly because programming computers is relatively difficult. As such it’s not often tenable to train students in how to create a computational tool prior to having them use it.

Which is where Loopy comes in.  Loopy is a very simple systems dynamics modeling tool where anyone can create a system and then see how its dynamics affect the system.  No programming is required, and the tutorial should take anyone <5 minutes to be able to render a system of their own interest.

Here’s an example of Loopy at work in a simple food web model that I created for this article:

See?  Not that hard (also, I totally understand that it’s “not that good”).

Tools like Loopy can help give students opportunities to model systems, without the high cost of entry that usually accompanies computational model construction.