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Transcript and student work are also available.

Robert B. Davis Institute for Learning. (1993). Continuing to explore fraction comparisons, Clip 4 of 7: Michael and Brian find four models to compare one half and three fourths [video]. Retrieved from

A89A90A91-FRC-CMPRF-CLIP004

In the fourth clip Michael and Brian worked together to compare one half and three fourths.
Michael built a model of an orange and red train, two dark green rods, and four light green rods. He then compared the length of three light green rods and one dark green rod and concluded directly that three fourths is larger than one half by one fourth. Two minutes later, researcher Amy Martino asked Michael and Brian to explain their model. Michael repeated his direct argument, and Brian agreed with his justification. Brian built a second model using the purple rod, two red rods, and four white rods. Michael tried to find another model, and he followed Brian’s suggestion to use another length train that was “even.” Michael built a model using a blue and yellow train as one, and two black rods as halves. He then tried to find a rod that could be one fourth of the train. After trying the purple rods and seeing that they would not work, he used reasoning to explain to Brian that the model didn’t work. Brian then built another model using a train of two blue and one red rod, two orange rods, and four yellow rods. He reasoned that this model also showed that three fourths was larger than one half by one fourth. Brian and Michael then decided to record their solution to the problem. Michael, with some assistance from Brian, found a fourth model, and they each set out to record two models and explain why their solution made sense. As in the previous session, Brian and Michael used their models to write a general solution and justification to the problem. As they spoke, they referred to the models that they had built to ensure that their justification paralleled the specific model that they had used to think about the problem. The researcher then approached them and Brian read his justification to her.

http://hdl.rutgers.edu/1782.1/rucore00000001201.Video.000067455

doi:10.7282/T3X63KHF

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.