Fraction as number, an introduction, Clip 2 of 8: Students model fraction problems

In the second of eight clips from this session, researcher Carolyn Maher said, “Someone told me that the red rod is half as long as the yellow rod. What do you think?" Danielle responded that the statement was not true, and justified her solution. The researcher then asked the students if the purple rod was half as long as the black rod. Alan and Erik, as well as Meredith and Sarah said that it could not be true because two purple rods were not equal in length to the black rod and that the two purple rods were “too large.” David, when asked during the whole class discussion to respond to the problem, replied similarly, saying “Two purples are too large.” Next the researcher asked the students if the red rod was one third as long as the dark green rod. Jackie, at the overhead, showed that a train of three red rods are as long as the dark green rod. Michael explained that by lining up three red rods below the green rod, one can convince others that the statement is true to justiy their solution. The researcher then asked the students what number name they would give the red rod if the green rod was called one. Sarah showed that since there were three red rods lined up under the dark green rod, the red rod would be called one third. Beth elaborated with a justification for why the red rod would be called one third by saying, “because if you put three on them it makes one whole.”Transcript and student work are also available.Robert B. Davis Institute for Learning. (1993). Fraction as number, an introduction, Clip 2 of 8: Students model fraction problems [video]. Retrieved fro