Use the following Interactive Activity to work on the problems below, which let you use the rods to try out representations and operations with fractions.
This activity requires the Flash plug-in, which you can download for free from Macromedia's Web site. For a non-interactive version, use Cuisenaire Rods or print several copies of the Rods Template (PDF) on stiff paper and then cut them out.
What rod would you use as a unit to do computations with fifths?
What rod would you use as a unit to do addition and subtraction with fifths and halves?
How are the combinations of rods you can use related to factors?
Model 1/2 + 2/5.
Model 3/5 - 1/2.
Model 3/5 1/2.
Model 4/5 1/2.
What rod (or combination of rods) would you use as a unit to perform the following computations with thirds and fourths?
1/3 + 1/4
3/4 - 1/3
The rod that you are using to represent "1" will need to be more than a single rod. In this case, it is best to choose the orange rod plus whatever rod you need to make the appropriate length. Close Tip
Use the Interactive Activity to explore operations with other fractions.
Video Segment In this video segment, Rhonda and Andrea use rods to model multiplication and division with thirds and fourths. First they must figure out what their model is going to be in order to do their computations. Watch this segment after you've completed Problems B2 and B3.
If you are using a VCR, you can find this segment on the session video approximately 11 minutes and 42 seconds after the Annenberg Media logo.