Content Area: Math

 

Index: 4.1C Grade 2 CPI 2

 

Standard: 4.1 - Number and Numerical Operations

 

Strand: C - Estimation

 

Cumulative Progress Indicator: 2 - The student will determine the reasonableness of an answer by estimating the result of computations (e.g., 15 + 16 is not 211).

 

Grade: 2

 

Sample Activities:

 

·        Students are regularly asked if their answer makes sense in the context of the problem they were solving. They respond with full sentences explaining what they were asked to find and why the numerical answer they found fits the context reasonably, that is, why it could be the answer. For example, first graders might be asked to decide if their answer to the following problem makes sense: Mary made 27 cookies and Jose made 15. How many cookies did they make in all? Some responses might indicate that the answer should be more than 20 + 10 = 30 and less than 30 + 20 = 50. Other students might say that they know that 25 and 15 is 40, so the answer should be a little more.

 

·        Students estimate reasonable numbers of times that particular physical feats can be performed in one minute. For example: How many times can you bounce a basketball in a minute? How many times can you hop on one foot in a minute? How many times can you say the alphabet in a minute? and so on. Other students judge whether the estimates are reasonable or unreasonable and then the tasks are performed and the actual counts made

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·        Second-grade students are given a set of thirty cards with two-digit addition problems on them. In one minute, they must sort the cards into two piles: those problems whose answers are greater than 100 and those less than 100. The correct answers can be on the backs of the cards to allow self-checking after the task is completed.

 

·        Second-grade students are given a page of addition or subtraction problems in a multiple choice format with 4 possible answers for each problem. Within some time period which is much too short for them to do the computations, students are asked to choose the most reasonable answer from each set of four.