By Gail M. Atley

Do you have a collection of your favorite, classic laboratory experiments? Why not upgrade them to provide new lab experiences with the experiments!

Classic lab experiments written before the adoption of NGSS use a standard format. First, an Objective gives a explains the purpose of the experiment. An Introduction reviews some key topics along with a couple of equations or diagrams. This section is typically “TL;DR” (Too Long; Didn’t Read), and you and your students skim over this part. Next, there is a list of Safety Precautions, a Materials List and then the Procedure which is more like a “To Do” list. Students are required to answer a few ‘Pre-Lab’ questions and they are set loose to conduct the experiment. The final action is a Lab Report, which recaps the information with a data table and a few lines of a summary. 

Even after all of the work you do to prepare, and all of the materials that are used, the results from the students’ lab reports are often disappointing. The report’s data table is complete, but the analysis of what happened is lacking depth, and it is often difficult to determine whether the students made any real connections between their learning and the experiment at all.

Classic lab experiments provide the teacher with formative assessment data on their class’ laboratory skills, ability to follow directions and their powers of observation. Revising the classic lab experiments with Science and Engineering Practices (SEPs) gives the teacher deeper insight into the students’ understanding of what they observed at various points in the process.

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You can transform your classic lab experiments into Next Generation Science Standards (NGSS) Science and Engineering Practices (SEPs) superstars by adding a meaningful reason to conduct the experiment, changing the order and task flow from the original format. You can give, and giving students multiple opportunities to create questions, talk with peers and do the experiment more than once. 

One of my favorite chemistry lab experiments is “Tick Tock, a Vitamin C Clock” (TTAVCC), written by Steven W. Wright. This experiment uses household chemicals and orange juice to demonstrate the chemistry behind an iodine clock reaction. Students make three solutions with different concentrations of vitamin C along with starch and iodine. The clear solution turns instantly blue-black once the vitamin C is depleted in a multi-step chemical reaction. It is a ‘wow-wee’ lab that always delights the students. They scream with delight and pull out their phones to make videos. They jot down how long it takes for each solution to change color, and they even figure out that the solution with the highest concentration takes longer to change color. Mission accomplished, right? Not exactly.

Over the years I realized that this simple, classic lab experiment can be easily modified to meet the NGSS standards, and provide the students at all skill levels with a meaningful experience. If the excitement of the outcome overpowers students’ evidence-reasoning process, and you end up with, that was cool, instead of your intended outcome. 

Five Steps + 5 SEPs = Superstar Results:

Begin with the end in mind. Classic lab experiments and the subsequent student analysis and reflection have the potential for rich scientific discourse on multiple topics. Decide what you want students to learn during this experience, which skills you want them to practice, and how they will articulate their understanding. If multiple ideas are compelling, consider running the experiment more than once during the school year. For example, the TTAVCC experiment can help students learn then discuss clock reactions, rates of reaction, concentrations of solutions, stoichiometry and more. I have even used this experiment to discuss ways to verify manufacturer’s claims on the amount of vitamin C contained in sports drinks and orange juice products. 

Let’s give them something to talk about. It’s no secret that students are more engaged when they are working to explain a phenomenon or a discrepant event. We know how to provide an NGSS-style engaging opening for the unit of study, but consider the impact of creating a phenomena opening for the next lab experiment too. What about doing a hands-on maker or modeling session before you prep your students for the lab? Or, play a video or a scene from a popular show or series that is relevant to the subject. For the TTAVCC phenomena, I collect different types of drinks containing vitamin C. Students do taste testing, then I give them time to create questions on sticky notes about the drinks based on the label and the taste test. All of the questions are gathered on a poster board and organized by topic and interest. For example, one essential question could be, “How can we determine how much vitamin C is in each drink?” These types of activities allow the students to co-create the experiment’s Objective with you, and practice SEP#1 – Defining Problems for Engineering and SEP #2 – Asking Questions for Science. 

Reorganize the order of the classic lab experiment. Give the students the Procedure and Safety Precautions and allow them to make a sample run, or do a whole class demonstration. At each stage of the experiment, ask them to write answers to the question, “What do you predict is going to happen next?”. Once the sample run is complete, allow students time to process what they have observed with peer to peer discussions. Go back to the sticky note poster board and ask, “Were we able to answer any questions with our current results?” 

Take the Introduction information and deliver it in smaller chunks. Give students time to draw pictures or to make models of the mechanism or phenomenon. Perhaps students can make a skit or flow chart to describe what is happening during the experiment. Practicing SEP #4 – Developing and Using Models will give you insight into the students thought processes and time to correct any misconceptions. Now the students are armed with questions to be answered, a preview of what to expect, and a model of what is really going on throughout the experiment. 

Plan to conduct the classic experiment more than once. Once the data table is complete, there is more work to do. Now that the evidence is collected, students should go back to their original questions. At this point, they may be able to devise some claim-evidence-reasoning statements to summarize their initial findings. Use SEP #4 – Analyzing and Interpreting Data as the starting point. Allow the students to devise their own experiments to answer the essential question and any others that are not yet answered. Encourage them to be creative with the materials available. For example, if the class agrees on what should be done next, then the experiment can be run as a whole-group activity. This gives students practice in SEP #5 Planning and Carrying Out Investigations using the classic experiment as a guide.

Analyze. Reflect. Argue then Repeat. Plan sufficient time for students to compare their results to the models created in the Introduction information phase of the experiment. Create opportunities for the students to reflect on their progress in understanding the concept as a result of conducting the experiments. Allow the group to argue about what the results mean. If the classic lab experiment covers multiple topics, archive the data and discussion transcripts for a future date. 

With a few minor changes to classic lab experiments and a little more time, your students will be able to build skills in science and engineering practices and engage in rich, scientific discourse. 

Gail M. Atley is a high school Chemistry teacher at Animo Watts College Preparatory Academy in Los Angeles is CSTA's High School Director. Contact her at g.atley@att.net

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