Content Area: Math

 

Index: 4.1C Grade 4 CPI 2

 

Standard: 4.1 - Number and Numerical Operations

 

Strand: C - Estimation

 

Cumulative Progress Indicator: 2 - The student will construct and use a variety of estimation strategies (e.g., rounding and mental math) for estimating both quantities and the results of computations.

 

Grade: 4

 

Sample Activities:

 

·        Students use rounding to create estimates, especially in multi-digit addition and subtraction. They do so flexibly, however, rather than according to out-of-context rules. In a grocery store, for example, when a person wants to be sure there is enough money to pay for items that cost $1.89, $2.95, and $4.45, the best strategy may be to round each price up to the next dollar. In this case then, the actual sum of the prices is definitely less than $10.00 (2 + 3 + 5). On the other hand, to be sure that the total requested by the cashier is approximately correct, the best strategy may be to round each price to the nearest dollar and get 2 + 3 + 4 which is $9.

 

·        Students are shown a glass jar filled with about two hundred marbles and are asked to estimate the number in the jar. In small groups, they discuss various approaches to the problem and the strategies they can use. They settle on a strategy to share with the class along with the estimate that resulted.

 

·        Students write about how they might find an estimate for a specific problem in their journals.

 

Sample Assessment Questions:

 

·        Estimate 39 x 11. The product is between what numbers?

o       A. 30 and 80 

o       B. 100 and 150 

o       C. 300 and 800

o       D. 1000 and 1500 

 

The correct answer is C.