discrepant events science experiments

Why You Should Be Using Discrepant Events

Planning , Science

One of the best ways to engage students in science at the start of a new unit is to use a discrepant event. Discrepant events pique students’ interest and leave them craving the knowledge that you plan to teach them. Students are often left begging you to tell them “how did that happen?” That’s the kind of engagement we need (and want!) in science. It’s a win-win!

Are you looking for ways to engage and motivate your students in the science classroom? Consider using discrepant events! This research based teaching strategy is the best way to get students hooked and make them say "how did that happen!?" This is a strategy you SHOULD be using in your science teaching!

What is a Discrepant Event?

A discrepant event is a surprising and paradoxical outcome that is not what an observer would normally expect. A most common example of a discrepant event would be oobleck. Most children (who have never seen it before) would not expect it to have both properties of a solid and properties of a liquid. Nor would they expect it to roll into a ball and form, but immediately spread out as soon as the “ball” is placed on the table.

Why Should You Use Discrepant Events?

The largest reason is that students will become hooked on science. To them, this will appear to be “magic” and their ears will be wide open to understand just how that worked. Then they will be ready to “amaze” their friends both with the “trick” and then with their “smarts.”

But there’s also the fact that it’s a well-researched and well-documented teaching strategy! It helps teachers assess students’ knowledge and target any misconceptions.

Further, it helps students develop more of a scientific mindset. When a scientist makes an observation, something may spark their curiosity which will then lead to an investigation or research. This is exactly what inquiry science is – and exactly what NGSS wants us to do .

It develops critical thinking and problem-solving skills – something all students need to develop more of.

Examples of Discrepant Events

In the first video below, the mini marshmallow is placed in a syringe and the end is capped. Then, as the plunger is pulled back the marshmallow increases in size. When the plunger is pushed in toward the marshmallow, it decreases in size. This would be a great example to do on a doc cam or for students to do themselves. It’s best to use a syringe that is a bit longer (and not necessarily as wide as the one I used in the video).

This is one of my favorite examples. In the video below, you have two candles that are burning. After about a minute of both candles burning, you blow one out. Then you hold the one candle that is still lit over the unlit candle’s smoke. The unlit candle will then light. It’s exciting to watch the flame “jump” from the lit candle to the unlit candle without actually touching the flame to the wick! Of course, you don’t have to use two candles. You can also use a candle with a match. Just relight the candle using a match and the smoke. This discrepant event is sure to excite your students and make them say, “how did that happen?! “

In this example, I asked my husband to kindly volunteer for me so I could record the demonstration. First, my husband takes a long paint stick and places it under two pieces of flat newspaper. (Make sure when you do it, you smooth out the air pockets between the newspaper and the table. You’ll notice this in the video.) My 5-year-old twins were around, so I went ahead and asked them what they thought would happen. They reacted just as most kids do: they thought the stick would pop up through the newspaper (tearing the newspaper) and then land on the floor. I mean, who would really believe a newspaper would break a paint stick? When you watch the video, I slow it down when my husband breaks the stick so you can see there’s no crazy business with the stick and newspaper. Then you can see the newspaper does not tear. Try it yourself. 🙂

In this example of a discrepant event, two empty aluminum cans are placed on parallel straws close to one another. Then a straw is placed near the cans that are apart from one another. Then I blow between the cans and instead of blowing the cans apart, as one would expect, the cans actually move toward one another.

These are just a few examples of discrepant events. There are lots of them out there. Just do a quick google search to get more ideas, or follow me to discover more!

How to Use Discrepant Events in the Classroom

Before demonstrating any discrepant event, first, ask students what they think could happen. Emphasize that there is no right or wrong answer. Then after the demonstration, have students write down any questions they have along with what they think is occurring. Ask the students guiding questions to help facilitate the discussion. Depending on your goal, you can have students work through the scientific method and processes, or you can have students research. Ultimately, make sure that students are never left hanging and that you do explain what did occur and how it happened.

After your first time using a discrepant event in the classroom to introduce a science concept, not only will your students be engaged, motivated, and hooked on science, but so will you!

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Back to school with discrepant event science, asking questions.

My first demo begins with two black plates upon each of which I place an ice-cube. Within seconds, students notice a difference between what is happening to the ice cubes. As a puddle forms around one cube, the other remains solid ice showing now signs of melting. I then ask students to record two questions, the answers to which they think will help them understand the difference between the two ice cubes. Students share their questions (Are the ice cubes both made of the same substance? Is one plate hotter than the other?) and explain why they the answers to their questions will help them more fully understand what’s going on. After a few minutes of sharing (but not answering) questions, one student invariably suggests moving the not melting cube to the other plate. When it begins melting and students exclaim that it must be that the one plate is hotter than the other, I pass around the plate sitting under the rapidly melting cubes. To students surprise, it is not warm but instead ice-cold! We continue the discussion and questioning, eventually discovering that the plates are made of different materials (wood vs. metal) and discussing conduction and relative temperature. In this 20-minute investigation concludes with a discussion of how asking questions helped us (and scientists) understand an unexpected phenomenon.

Ideas & Resources

My discrepant event introductory lessons typically include five different demos, each practicing a different skill (recording observations, asking questions, recording data, making predictions, etc.). Below are some of the materials I use in my classroom and resources on how to bring discrepant event science into your classroom.

From NSTA Press: Author Thomas O’Brien created his Brain-Powered Science series for educators who love to surprise and challenge their students with unanticipated results. Using his inquiry-oriented experiments based on the science of discrepant events—hands-on explorations or demonstrations in which the outcomes are not what students expect—teachers can challenge students’ preconceived ideas and urge them to critically examine empirical evidence, draw logical inferences, and skeptically review their initial explanations with their peers.

Ice Block Demo – As described and pictured above.

Self-Inflating Balloons – A sealed, opaque mylar balloon mysteriously begins to self-inflate

Happy & Sad Balls – A ball suddenly stops bouncing after being secretly switched for one made of a non-elastic material

UV Detecting Beads – Beads change from colorless to vibrant colors, but only in some types of light.

Sinking & Floating Spheres – Two spheres with identical masses respond differently when placed in a bowl of water

Astro Blaster – A red ball mysteriously bounces five times higher than the height from which it was dropped.

About The Author

Mike matthews.

Michael is a National Board Certified Science teacher. He currently serves as the Director of Curriculum and Program Innovation at an Independent School in the San Francisco Bay Area.

About the Founder

Mike is a National Board Certified Science teacher. He currently serves as the Director of Curriculum and Program Innovation at an Independent School in the San Francisco Bay Area.

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Promoting Scientific Inquiry Inside and Outside of the Classroom

Exposing students to discrepant events and online simulations can spark wonder and motivate them to investigate science beyond the classroom.

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Middle school student takes notes during virtual learning session

Scientific inquiry continues to be conflated with any instructional activity in which students ask questions and seek answers in the learning process, but scientific inquiry is much more than the act of inquiring. Even before the pandemic, teachers struggled with adopting not only the higher levels of scientific inquiry into their classrooms but also reaching a clear consensus of what science as inquiry entails. The abrupt transition to virtual teaching led to many students passively watching their teachers engage in science far removed from the scientific-inquiry process.

The four levels of scientific inquiry establish a framework for engaging students in science as inquiry:

Confirmation inquiry: This is often considered level zero, as inquiry is absent. Students complete an activity with prescribed problems and procedures in which they are already aware of the solutions.
Structured inquiry: Students follow procedures for an investigation of a novel topic.
Guided inquiry: Students determine their own methods to collect evidence for a teacher-posed problem.
Open inquiry: Students formulate their own questions and methods for on-topic investigations in the curriculum.

With virtual teaching, there are many challenges integrating the higher levels of scientific inquiry, as students may not have the supplies or materials they would in the classroom. They also may lack the necessary safety equipment or adult supervision. But there are still effective ways to teach scientific inquiry to students learning remotely.

3 Strategies for Teaching Scientific Inquiry Virtually

1. Demonstrations with discrepant events. With virtual learning, it’s very easy to fall into the trap of performing demonstrations while students watch passively. Guarantee that all demonstrations are at least structured inquiry by carefully selecting discrepant events to spark curiosity and motivate students for further investigations.

Discrepant events cause cognitive dissonance due to the surprising and unanticipated results. Baffled students naturally generate many questions that can be used for an extension activity, such as an open inquiry in which students test their explanations. Working through the cognitive dissonance can have profound effects on learning. Thomas O’Brien has three books published by the National Science Teaching Association with discrepant events for students from fifth grade to 12th grade.

If a discrepant event is based on household materials that students typically have accessible, they first meet in groups to brainstorm their questions, predictions, and methods for testing the discrepant event. Even without access to the materials, groups can work together by engaging in effective team communication by assigning one student to be the manipulator of the materials while the others serve in roles such as researchers. If the discrepant event requires materials that are not readily available, students will similarly work in groups to brainstorm and then instruct me in how to manipulate the demonstration for the entire class. Together as a group, we will work through the discrepant event to explain the phenomenon.

2. Simulations with PhET. PhET simulations by the University of Colorado have been an integral part of teaching science as inquiry for a long time. Since 2002, scholars have created 159 free interactives for physics, chemistry, math, biology, and earth science in 95 languages. With almost 3,000 coordinating lesson plans available, it’s easy to find inspiration to create your own.

These simulations are investigative, meaning students actively engage in all levels of inquiry and manipulate the simulations accordingly. They are not just passively clicking and watching. One of my favorites is the energy skate park , which, among other things, allows students to design a skate park using the concepts of mechanical energy. PhETs can easily be confirmation or structured-inquiry lessons by providing students a set of instructions to complete for the simulation, and PhET provides many lesson plans for each simulation. However, teachers can adopt a guided-inquiry approach by providing a central challenging question to the students. Students have autonomy to manipulate and determine their own methods for answering the teacher-posed questions.

It’s even possible for students to engage in open inquiry with PhETs or other simulations. When engaging my students in open inquiry, I will first briefly model the basic functions of the simulation. Then students are presented the following four prompts to scaffold the development of their research questions, hypotheses, and methods for the investigation:

1. Describe your topic in general. How does it act?

2. What can you change or manipulate with the simulation? Brainstorm all possibilities. These are the independent variables.

3. What can you measure or describe about the response in the simulation? Brainstorm all possibilities. These are the dependent variables.

4. Review your responses, and select an independent variable and dependent variable. Develop your research question, prediction, and methods.

3. Investigations. My best virtual homework assignments have been guided and open-inquiry investigations. Students have increased motivation to perform an investigation rather than complete a worksheet. The important thing is to develop scaffolding that guides students in their thinking processes. I start small. These do not need to be long-term projects, but rather activities that students can complete within an hour, a day, or a week.

We begin investigations with the four prompts listed above for simulations once we have established a topic. The groups debrief their responses using a jigsaw approach so that each member of the group is accountable to share and seek feedback from students in other groups. Students organize their data into a CER (claim, evidence, and reasoning) template that they again will share using a jigsaw approach in mixed groups.

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Discrepant Event Science in the Classroom

Back to school with discrepant event science.

by Mike Matthews

After a restful summer (which included a move to a new school!), classes are finally back in session! I always begin the year with a set of activities that challenge students to practice science process skills (observing, recording data, asking questions, etc.). My approach includes a series of quick “discrepant event” demos that captivate (and baffle) my students. From trying to figure out why two ice cubes melt at dramatically different rates to brainstorming explanations for how a sealed opaque balloon suddenly starts self-inflating, these demos engage students, assess their science skills, and emphasize the processes and habits that scientists use to inquire about the world around them.

Asking Questions

Students share their questions (Are the ice cubes both made of the same substance? Is one plate hotter than the other?) and explain why they believe the answers to their questions will help them more fully understand what’s going on. After a few minutes of sharing (but not answering) questions, one student invariably suggests moving the not melting cube to the other plate. When it begins melting and students exclaim that it must be that one plate is hotter than the other, I pass around the plate sitting under the rapidly melting cubes. To students’ surprise, it is not warm but instead ice-cold!

We continue the discussion and questioning, eventually discovering that the plates are made of different materials (wood vs. metal) and discussing conduction and relative temperature. This 20-minute investigation concludes with a discussion of how asking questions helped us (and scientists) understand an unexpected phenomenon.

Ideas & Resources

Amazing Ice Melting Blocks

As described and pictured above.

Self-Inflating Balloons

Choositz Decision Balls

A ball suddenly stops bouncing after being secretly switched for one made of a non-elastic material.

UV Detecting Beads

Beads change from colorless to vibrant colors, but only in some types of light.

Steel Sphere Density Kit

Two spheres with identical masses respond differently when placed in a bowl of water.

Seismic Accelerator

A red ball mysteriously bounces five times higher than the height from which it was dropped.

Brain-Powered Science

This entry was posted on Friday, September 9th, 2016 at 12:37 am and is filed under College level , Elementary level , High School level , Middle School level . You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response , or trackback from your own site.