Across Content Areas

Science

Scientific ideas are often counter-intuitive. Common sense leads us to believe that day and night are caused by a moving Sun, that air is weightless, that heavier things fall faster, and that most of the matter in a plant comes from the soil. Science contradicts these beliefs.


More challenging still are the ideas about things we cannot observe: that a hard wooden desk is made of tiny atoms, most of which are empty space, that we evolved from other animals, and that diseases are caused by tiny, invisible microorganisms that can be found just about anywhere.


We know from research that everyday ideas about scientific phenomena are very resilient.[1] Even when students provide the expected answers on exams, they often revert back to their unscientific ideas outside of the classroom. Time spent reasoning in discussion, including exploring why the common-sense idea might be wrong, provides the opportunity to think more deeply and to fundamentally change common, unscientific conceptions.

Discussion shows students that learning science is really about ideas, not committing to memory a miscellany of facts and definitions. The questions about the material and living world at the heart of the scientific enterprise are:

  • What is it?

    What is it? is central to teaching science. Students have to learn about entities and concepts that they have never met or imagined, e.g., atoms, cells, solar system. Discussion helps students to make important distinctions— such as the difference between: energy and power; respiration and breathing; an atom and a molecule; a chemical change and a physical change. They can also be asked categorical questions, such as: Is a dolphin a fish? Is a hyena a decomposer? Should Pluto be considered a planet? 

  • Why does it happen?

    Why does it happen?—the causal explanations at the heart of the scientific enterprise—can be explored with questions such as: where does the water that appears on a cold can of soda come from? Why does the water in puddles disappear, and has it gone forever? Why does the Sun move across the sky over the course of a day? Why can I lift something twice my weight with a lever? 

  • How do we know?

    How do we know? can be asked about any scientific phenomenon.  Science is an argument based on evidence, and discussing what the evidence is for scientific beliefs is an important part of learning science. For instance, students might be asked: How would you convince your sibling that matter is made of atoms? How do we know that germs exist? What is the evidence for the idea that species have evolved from other species? How do we know that day and night are caused by a spinning Earth and not a moving Sun?

While these may have textbook answers, research shows that discussion significantly enhances students' understanding and recall.[2][3][4][5] Importantly, these three essential questions can be the focus for lively discussion. 

There are three instructional purposes for which discussion is valuable in the science classroom, each of which is likely to be important during the teaching of any science topic:

Exploring and Challenging Students’ Existing Conceptions

All knowledge has to be built on what we already know. Eliciting students’ current thinking—and their existing “funds of knowledge”— is an essential precursor to inquiry. Research confirms that if students' current thinking is not engaged, they will hold onto their naïve ideas even if they are able to produce the expected answer for a test.[6] To be clear: just exploring what students are currently thinking is not the goal; in fact, such a discussion may reinforce everyday ideas which would be counterproductive. The purpose of such discussion is to surface the different ideas and to sow the seeds of doubt that there is more to explain than the students might realize.


A good example, for instance, is asking students to make a prediction e.g., whether an ice block will melt faster on a wooden block or a metal block. Most students predict the wooden block arguing that it is warmer. In reality it melts much faster on the metal block which disturbs their mental models, thus requiring rethinking.


Another example can be found in the clips below.

The 6 clips below are from:

Is a Seed Dead or Alive?

Science • Grade 2

This discussion is intended to get students’ current understanding on the table. Note that the teacher helpfully clarifies the difference between fact and opinion. She is signaling that they are going to be having a discussion about their ideas (which she labels as opinions), and that scientific evidence will come later. By giving students time for a quick write, she ensures that every student has had a chance to think about the question before discussion begins. If we want students to revise or replace their current thinking with scientific thinking, each student’s current thinking must be engaged.

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    The idea of a continuum is interesting because it gives students the option of expressing a more complex position than just alive or dead. They may note that seeds have some characteristics that make them seem alive, and others that suggest they are not alive.

We see immediately that students have used the opportunity of the continuum well. They generate nuance: the seed shell is not alive, but the plant that comes out of it is alive. The plant needs water to grow, but “because it creates a living thing, then it has to be living.” This is a clear claim for which the student has provided evidence: the plant that emerges is alive.

In this segment students are putting what they know on the table. Charlene wants to be clear that water isn’t enough for a plant to come to life. It needs sunlight as well. Student 4 adds information about plant hybridization. When students have the opportunity for discussion, the shared ownership of learning enhances their engagement and cognitive growth.

With a few ideas on the table the teacher breaks students into small groups to discuss their thinking with their partner(s). The back and forth between whole group and small group allows students to have the benefit of ideas to work with, but also the opportunity to process and formulate their own ideas. Note that the teacher stays in questioning mode, avoiding making any judgements of their reasoning. This gives students the opportunity to further develop their ideas and to deepen their reasoning.

In this segment, students’ respond to and build on each other’s ideas very directly. Dylan has moved toward the “not alive” end of the spectrum; he claims that without water and sun, the seed wouldn’t grow. So the seed by itself is not alive. McKenna both agrees and disagrees. She acknowledges that the seed needs things to grow, but by pointing out that the plant needs those same things (and the plant is alive), that this is not a disqualification.

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    Avery makes an interesting analogy: when we are born, we need food and water, but we are alive. The analogy is not perfect, because a seed is not yet born. And Child 16 picks up on this point. If the seed cracks open from growth inside, then it is alive. But it may never crack open and grow. The sophistication of these exchanges is entirely an outgrowth of considering each other’s arguments and formulating their own ideas in response.

In this final segment, the teacher builds on child 16’s idea that the seed may never grow by calling attention to the seeds in a bag in her cupboard. Many more students seem willing to claim that those seeds are dead. As they go back to their desks to write, the pieces are in place for students to engage with the idea that seeds are dormant - essentially in a deep sleep. The discussion has fed them ideas that leave them well-prepared to think and write individually and develop a more nuanced understanding. And having invested in the discussion, it is far more likely that when they move from their ideas to the common scientific conception, as the teacher suggests they will, that conception will have far greater and more lasting meaning.

Developing an Understanding of a Scientific Term or Concept

Much of science is about making sense of what things exist in the world, how they function, and how they are similar to and different from each other. Categories, definitions, and conceptual distinctions are therefore at the heart of the scientific enterprise. Whereas the initial stages of discussion seek to explore students’ existing conceptions, the goal of this stage is to introduce a scientific concept and/or category, to give students time to work with the idea in order to more fully understand it, and to explore the evidence that exists for the scientific conception. Thus, the examples may be the same, but simply asking students what they think is not enough.

In this video, the teacher has an upper elementary class outdoors and is using the context of lots of rotting vegetation to discuss what a ‘decomposer’ is. 

The 4 clips below are from:

What is a decomposer?

Science • Grade 5

This lesson begins with the teacher using IRE to recall what students have learned are the three categories of decomposers. The scientific definition is given by the teacher. Then the teacher asks students to think about what belongs in the category. When a student makes a suggestion in response to the teacher's open question that hyenas might be decomposers, the teacher does not shut down the conversation; rather he uses it as a means of exploring what a decomposer is. He turns the question back to the students indicating that this is a good, discussable question. 

The teacher seizes the opportunity of a jumping cricket—which has clearly captured the attention of the students—to explore the question of whether a cricket is a decomposer. This is a helpful move on the teacher’s part because crickets fall into a gray area. The student who answers that it is not a decomposer is, technically, correct: it is an invertebrate (not one of the decomposer categories), but it primarily eats grass and other plants and thus falls into the scientific category of a consumer, not a decomposer. However, some crickets will also eat dead organic matter in the soil, and when they do, they act as decomposers.

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    So the student is correct that eating grass means the cricket is not, primarily, a decomposer, but he’s not clear that the scientific definition the teacher repeats disqualifies the cricket as a decomposer. This illustrates an important benefit of discussion—it causes students to question their understanding in the service of developing more accurate or nuanced ideas

In this segment, we see students engaged in careful reasoning. The student who argued that anything that eats is a decomposer is generalizing in a way that is thoughtful; he has concluded that eating, the very process of breaking food apart to extract nutrients, is decomposing. When the teacher asked about humans, a student offers an example of people eating steak made from dead cows. He is almost ready to abandon the idea of humans as decomposers until another student points out that poop becomes part of the soil. Humans are considered consumers rather than decomposers. But the teacher focuses more at this point on students’ reasoning.


Mike challenges the idea that everything that eats is a decomposer. He argues that trees eat, but he doesn’t think they poop. They have wandered into unexpected territory. Trees are producers; they are very different from consumers and decomposers. The teacher is in a tight spot; he chooses to tell students some things he knows about trees, but lets them consider how those things relate to decomposition.

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    While defining and classifying are important elements of understanding the material world, students are unlikely to remember definitions given to them. The students' definitions in this video are original and raise good questions - are hyenas decomposers? Are trees decomposers? If not, why not? Opened up here are broader issues of how entities are defined in science than merely the answer to the question: what is a decomposer? Moreover, the students are given agency by allowing the discussion to be directed by their questions.


    As a teacher you may wonder whether students have understood the scientific definition of a decomposer. The answer is “not yet.” The teacher has explored student thinking about the category of decomposer, but has not explored the purpose of the category: to distinguish decomposers from producers and consumers. The value of this discussion would be greatly enhanced if students were to be given an assignment to explore the scientific distinctions between producers, consumers, and decomposers, and to discuss where hyenas, humans, and trees belong.


    But you can evaluate the outcome for yourself: after this discussion, are students more or less likely to think about the food cycle again? Will they be more or less confident about asking questions and sharing observations in the science classroom? Are they more or less likely to have a positive disposition toward science? Do you think it is an engaging, unusual and productive discussion?

Engaging in Collaborative Inquiry

The third purpose for discussion in the science classroom is inquiry focused; an attempt to explore why something happens and/or to answer the question of how we know. In this phase, the goal of discussion can be to eliminate poor or flawed ideas, develop an explanatory model and examine the evidence for a particular idea.

In all cases, the ultimate goal is to establish a consensus around one interpretation which can be defended against criticism. This is a model of the process by which science builds reliable, trustworthy knowledge.

The question being discussed here is “Why does clicking the disk on a reusable hot pack result in the release of heat?” [ see illustration]. The video shows one group of students discussing what might be the possible explanation. The phenomenon is puzzling as there is no visible source of heat. So the question students are struggling with is: where is the heat coming from? As you watch, consider:

  • Has this been a productive discussion? 
  • What was the value of asking the students to engage in this activity? 
  • If this were your classroom, would you do anything differently, and if so, what? 

The 5 clips below are from:

How do Hotpacks Release Heat?

Science • High School Chemistry

As discussion begins it’s clear that students have mastered some important scientific concepts. The first student frames the phenomenon in terms of a reaction, caused by the disk clicking, creating a change in some of the molecules (from liquid into solid). The very act of using scientific concepts to describe a phenomenon is an important opportunity to reinforce understanding of those concepts. The second student thinks he may have the answer: he says clicking the disk adds to the activation energy. But he stops in his tracks as he attempts to explain it. He realizes: “I don’t understand either why exactly that happens.” That awareness of the limits of one’s understanding is an important affordance of APT. It sets the stage for learning.  

Students begin down a path of trying to explain the crystallization by the particular force: is it clicking or is it flipping to the other side? Student 1 thinks the flipping is adding the force that explains crystallization. Student two shifts the conversation to the unexplained phenomenon: why the energy makes the liquid a solid. From the materials they have in hand, Student 2 reads the explanation: “you have a little bit of force and create a point for it to start crystalizing.” He realizes he has just read the explanation, but adds, “I just don’t understand why that happens.”

The teacher has remained quiet up until now allowing students to figure out what they do and do not know. He recognizes that they’re stuck. They don’t know why crystallization is happening. He reinforces their questioning about the change in molecular structure and focuses their attention on the structure of the disk. As they discuss, student 2 hits on the important point: “I would imagine that there are divots…because then that will provide a point for it to crystalize.” But he realizes that’s only part of the explanation. He adds, “why exactly does the sodium acetate give off energy at like approximately 130 degrees…Does it store energy from boiling? If you super cool it, what happens when it crystalizes to give off heat? Bingo! The teacher says just enough to let them know to explore this further.

In this segment students demonstrate how much they know about phase change and entropy. They use the terms endothermic and exothermic reactions, and they know that energy is greater in a liquid state than a solid state. They understand changes in the motion of molecules, but they are not focused on the breaking and forming of bonds until the teacher nudges in that direction. But there is a misconception now in the way; Student 2 says that to bond it needs energy (when it is breaking bonds that requires energy, and forming bonds that releases energy). 

Students have focused on entropy and have identified a source of confusion: the relationship between entropy and temperature. Student one points out that an increase in entropy would explain the heat energy. But they later realize that moving from a liquid to a solid has reduced the entropy. Thus, they conclude entropy can’t be the thing causing the heat. Their mistake is not to consider the entropy of the whole system, which has increased.

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    The activity assigned to students includes consideration of several claims, which can be useful in a small group discussion for focusing students’ thinking if they have gone down an unproductive path. But in this case, the questions do not help students get beyond their misconception regarding bonding. 


    In the end, the teacher allows the students’ puzzlement to remain. Whether this is the best instructional move is an open question. We do want students to understand the scientific explanation for the phenomenon. One thing is for certain, however. These students are very aware of what they don’t understand. Having invested time in thinking this through, they are far more likely to seek out that information than if they had simply read it in a textbook or were told the explanation by the teacher; and will have a deeper and more meaningful understanding of the scientific explanation when it is offered. 


    And when they learn that energy is required for breaking bonds but is released in forming bonds, they are likely never to forget it.

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