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Transcript and student work are also available.

Robert B. Davis Institute for Learning. (1993). Comparing fractions and evaluating models that represent solutions, Clip 3 of 8: Sharing Alan's candy bar model [video]. Retrieved from

A83A84A85-FRC-CMPRF-CLIP003

In the third clip Alan presented another model to show the difference between one half and one third. He built a model using one dark green rod, two light green rods, three red rods, and six white rods, and showed that the difference between one half, or a light green rod, and one third, a red rod, is the length of the white rod, which he named one sixth. Jessica challenged Alan’s solution by saying that Alan was making a different size candy bar. Kelly and Jackie said that they agreed with Alan and countered Jessica’s argument. Jackie explained how one can make a model with a different size and suggested that Alan had used a different size model, which was in line with the rules that had been set. Michael also backed Alan’s argument and explained how the white rods should be called one sixth. Jessica agreed that that was true, but repeated that it was a different size candy bar. Erik contributed to the argument, saying that they had said that any one sixth was correct, implying that Alan’s solution was legitimate. Researcher Carolyn Maher asked the class what they thought about why Jessica was confused. Erik said that the issue that Jessica had was that the sixth wasn’t the same size, implicitly backing Jessica’s argument. Michael countered this, saying that the rod that was called a “whole” wasn’t the same size either, and implying that had resolved the problem. Jessica repeated her argument and Andrew attempted to clarify why Alan was correct. Erik then tried to back Jessica’s argument, noting that although Alan hadn’t switched candy bars within his solution, but that he had switched from the orange and red train that Jessica had used originally. The researcher asked the class what Jessica was confused about. Michael repeated his earlier reasoning, saying that Jessica was confused since there was a different size one sixth but that Alan was justified in what he did since he had also switched the whole. With this summary, Michael integrated Andrew’s argument into his own.

http://hdl.rutgers.edu/1782.1/rucore00000001201.Video.000067441

doi:10.7282/T3R21000

The video is protected by copyright. It is available for reviewing and use within the Video Mosaic Collaborative (VMC) portal. Please contact the Robert B. Davis Institute for Learning (RBDIL) for further information about the use of this video.