Measuring Up Prototypes for Mathematics Assessment (1993) / Chapter Skim
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Bridges
Bridges
Pages 43-52
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From page 43... ...
The teacher should present the task essentially as the "script" below specifies.
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From page 44... ...
Since the yet tow rod is 5 cm long, the length of the bridge is 5 cm." "The second bridge you are to build is a 2-span bridge made with two yellow rods and four red rods (as shown below)
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From page 45... ...
Note that the yellow rods are 5 cm long.
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From page 46... ...
6. How many yellow rods and red rods would you need to build a bridge that is ~ 85 cm tong?
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From page 47... ...
1 1 c. How many light green rods did you use?
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From page 48... ...
4. How many black rods and light green rods would you need to build a 56-span bridge?
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From page 49... ...
This is clone to be sure the student realizes that even in a longer bridge each light green rod except the ones on the end supports two black rods. (If the light green rods were moved in a half centimeter, so that they were flush with the ends of the black rods, the student might think that the entire configuration shown in the picture is to be
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From page 50... ...
The amount of time that this kincl of task requires is very much dependent on the students' prior experiences. Ch i Siren who are very familiar with using centimeter rods to mode!
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From page 51... ...
This is a setting in which children can invent their own styles of bridges and thei r own questions about them. More generally, bridge-bui~ding with centimeter rods can be used to explore other mathematical topics for example, in the area of primes and factors: "Can you build a bridge that is exactly 101 cm long, using spans of the same length?
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From page 52... ...
Questions 1 through 4 of Parts 1 and 2 are answered satisfactorily - that is, a pattern has been noted and extended to the bridges that are too long to construct with the available rods. Questions 5 and 6, however, are not answered appropriately; the general rule may be unclear or not universally applicable.
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