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DescriptionIn clip seven, researcher Carolyn Maher told the students to use the remaining class time to challenge their partners with problems using the rods. Erik asked Alan, “If a light green was one third,...
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DescriptionIn the fifth of eight clips from this session, researcher Carolyn Maher asked the class to give a number name for the red rod if the brown rod was called one. Danielle explained that it would be...
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DescriptionIn the sixth clip Erik and Alan worked on the task: Which is larger, one half or three fourths. Erik showed, using the orange and red train as one, that the difference between the two fractions was...
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DescriptionIn the second of five clips from this classroom session, Alan worked alone at his desk on a new task that the researcher, Amy Martino, had posed. He built models to find the difference between one...
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DescriptionIn the fourth of five clips from this classroom session, the researcher, Amy Martino, returned to Alan and questioned him about the third model that he had built for finding the difference between one...
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DescriptionIn the seventh clip, Erik and Alan worked to extend their model using the orange and red train to show fourths and halves. They concluded that three fourths was larger than two thirds by one twelfth....
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DescriptionIn the fifth clip Michael and Brian extended their model using the orange and red train to show thirds and twelfths in addition to fourths. They showed that the difference between two thirds and three...
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DescriptionIn the third clip, researcher Amy Martino then worked with Mark and Laura. Mark justified his solution using each model he built. The researcher asked Mark if he thought that a different model might...
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DescriptionIn the second clip, David and Meredith worked on building models to represent their solution to the problem: Which is larger, two thirds or three quarters, and by how much. David first built two...
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DescriptionIn the fourth clip Erik repeated the explanation of his model to the classroom teacher. His model consisted of a train of three orange and one dark green rod and lined up four blue rods. He lined up...
