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Transcript and student work are also available.

Robert B. Davis Institute for Learning. (2005). Early algebra, investigating linear functions, series 6 of 7, Museum problem, Clip 5 of 6: James modeling the Museum problem with rods [video]. Retrieved from

B19B20-ALG-VAR-CLIP005

In the fifth of six clips from an after-school enrichment session in an urban middle school, James, a 7th grade boy completing a unit about linear functions, has finished his written solution for the Museum problem. When researcher Markus Hahkioniemi asks James if he could use the Cuisenaire rods to model this problem, James begins by building a "ladder" with two rungs and counts the rods as he had for the earlier Ladder problem. He soon discards this model and instead indicates that each rod in his resulting group of eight should represent a craft piece and a value of three dollars. He concludes that the value of the eight rods or craft pieces would be $24 and that there would be a need for two more dollars for the entrance fee. He selects two additional rods, assigning each a value of one dollar, but keeps them separate from the others. Regardless of the questions from the researcher, James tenaciously holds to his interpretation that the different groups of rods represent different things and therefore have different values.
The worksheet wording for the Museum Problem:
The Museum Problem - Version One
A museum gift shop is having a craft sale. The entrance fee is $2. Once inside, there is
a special discount table where each craft piece costs $3.
How could you represent the total amount that you would spend if you were to buy any number of craft pieces at the discount price?
The worksheet wording for the Ladder Problem:
A company makes ladders of different heights, from very short ones to very tall ones. The shortest ladder has only one rung, and looks like this (we could build a model of it with 5 light green Cuisenaire rods.) A two-rung ladder could be modeled using 8 light green rods, and looks like this. Build a rod model to represent a 3-rung ladder.
How many rods did you use? How could you represent the number of rods needed if you were to build a ladder with any number of rungs?
The questions as posed to James:
How might you use the Cuisenaire rods to model the Museum problem?
What does each rod represent?
Is there a way that all of the rods can have the same value?

doi:10.7282/T3HQ3WWJ

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.