Claire Bove, Carnegie Scholar - CASTL K-12 Program, Carnegie Foundation

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Student explanations

Below is a sampling of work produced by 6th grade students as they studied geology. Click here to view work produced by 7th graders conducting an inquiry into density and buoyancy


My picture of what scientists do is that they try to describe and explain how things in the physical world work. How do cells divide? What is the mechanism for cell division? Or: what happens when you shoot a proton at another proton at high speed? And why does it happen? Or: what happens when there is an earthquake? And what causes it? Once you have a description and an explanation, you inevitably have more questions, which lead you to find out more.

When students have had some practice at explaining things in this way, and generating their own questions, when they develop a taste for this kind of endeavor, their explanations improve and the questions they pose become more sophisticated. One function of engaging students in discussions of this kind is to help them internalize the process of attempting to explain, and of finding that their explanations lead to new questions.

I often ask students, �What do you know about ____________, and what question do you have about it?� Here are some examples of what students have said in response to these questions.

 

Student explanations (click one to read it)
My commentary

I copied this paper, and the one that follows, from the journal of Student 5. Students write observations, notes, explanations, and questions in their journals. Every day there is a question at the beginning of class (the "Opener") and one at the end (the "Closer").   The Opener on October 27, 2003, was "Explain how or why earthquakes happen.   What question do you have about earthquakes?"   Student 5 answers: "Earthquakes might happen because the gravity pulls the Earth and gravity's pull shakes the Earth and only some parts feel it."   This is the explanation he gave before we started studying earthquakes, and it is an interesting naïve conception.   (Gravity does play a role, but you need to understand magma and convection currents and the crust before gravity fits into a sophisticated explanation.)   His explanation shows that he is really thinking about the question.

 

The next week, I asked the same question, and Student 5 answered, "Earthquakes happen because there are things called tech. plates and the tech. plates cause pressure and the magma enables the plates to separate."   At this point, we had done reading, seen videos, conducted an experiment, and talked a lot about earthquakes. His view of earthquakes now includes magma and tectonic plates and pressure.   He is moving to more standard conception of earthquakes.

In my view, practicing science means attempting to explain some physical phenomenon, and then working to deepen and clarify the explanation.   Before we started studying about earthquakes, Student 6 answered the question about how or why earthquakes happen like this. "Earthquakes are caused by the movement of the plates under earth's surface."   This student has a pretty good standard conception of earthquakes even before we start learning about earthquakes.  

Practicing the skill of explaining is a good way for students to gain independence in their thinking about scientific ideas.   Student 6 answers the question this way after a week of studying earthquakes: "Earthquakes happen because of the movement of the plates (tectonic) on the surface of the earth."   Her understanding is subtly different than it was last week.   She now sees the plates as being pieces of the crust, the part of the earth we stand on.  

Journal writing can be unspectacular.   It is not as pretty as a poster or report.   But it is a good way to find out what a student is thinking about a scientific concept.   I usually ask for an explanation followed by a question.   Sometimes the question can tell as much as the explanation about how a student is thinking about a concept. The questions Student 5 and Student 6 ask about earthquakes are not too revealing, but the last two pieces of work, below, show how questions can reveal student thinking.

 

This paper, and the next one, were written after we did an activity in which we used clay to make a model of sedimentary rock. The experiment is very fun and engaging, and the worry for a teacher is whether making a model with clay translates to understanding what the model stands for.   The handout asks the student to draw what happened in the experiment.   Students have had the kinesthetic experience of making the different layers representing sedimentary rock.   In drawing the picture, they experience it in a different form: drawing and labeling.   Student 7 makes boxes to show the three separate iterations of the experiment.

 

This paper asks the student to relate the model to the real thing (sedimentary rock).   Student 8 successfully identifies the most important points in the activity: "Minutes were millions of years in this project."   And "The flat clay was sand, the balls were rocks."   I gave students a list of words to use in their explanations to point them in the direction I wanted them to go.   How they put the words together told me whether they made connections between what they were doing with the clay, and the concept of the formation of sedimentary rock.

(This experiment, and the one that follows, is adapted from one in the GEMS book: Plate Tectonics, published by the Lawrence Hall of Science.   The images on the handouts were copied from that book.)

 

After the sedimentary rock activity, we did a simulation of what happens to sedimentary rock in an earthquake.   Student 9 revisits the activity by drawing pictures of what we did and explaining in words what happened in each part of the activity.   The clay model, which the previous week we learned took millions of years to build up, is placed on a wooden block device with a metal strap that allows it to slide.   The slippage of the layers beneath the rock can cause the rock to move apart suddenly.   Student 9 shows each part, including the tools we used.   

 

This task is similar to the one above, where students are asked to explain how the model is like the real thing, and how it is not like the real thing.   Student 6 answers the task by telling what stands for what in the model: "...we used clay to make another sedimentary rock."   And "We stuck wooden toothpicks in our rock to make a fence."   She explains the steps we did.   Then finally she says, "All of our measurements were approximately 3 - 5 centimeters.   That is almost the same amount the San Andreas Fault moves."   I think that this simulation helped this student understand that the movement of the plates is not just under the surface, but on the surface as well.    

 

On November 10, the Opener was "Explain how igneous rocks are formed."   Then, "Write one question you have about igneous rocks."   And finally, "Tell whether your question could be answered by an experiment."   The sequence: explain, ask a question, and then think about how to answer your question is the basis for cycle of inquiry.   Each part of the sequence is a science skill I am trying to help students develop. I also want them to have a lot of practice in putting the parts together like this.    

For his question, Student 5 wrote, "Could igneous rock melt when it falls into magma or lava?"   This question shows his understanding of the relationship between magma and igneous rock better than his explanation, "Igneous rocks are formed by lava that dries in the air."   The question reflects an understanding of magma as the hot molten form and igneous rock as the cool hard form of the same substance.   (He didn't get to the last part about an experiment to answer the question.)

 

For her explanation, Student 6 said, "Igneous rocks are formed from hardened magma/lava."   Her follow-up question was, "How long does it take for magma/lava to cool into igneous rocks?"   In our study of sedimentary rocks, one of the things we emphasized was the very long time it takes to form them.   Her question shows that she is thinking about differences between the two kinds of rock.  

When I ask students to say if their question can be answered by an experiment, I am hoping that they will think about what type of question can be answered by an experiment, as opposed to what type you would answer by looking it up (for example historical instances of volcanoes erupting).   Student 6 recognizes that her question can be answered with an experiment, and proposes a beautifully simple experiment to do so.