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Content Area: Math
Index: 4.1C Grade 2 CPI 3
Standard: 4.1 - Number and Numerical Operations
Strand: C - Estimation
Cumulative Progress Indicator: 3 - The student will explore a variety of strategies for estimating both quantities (e.g., the number of marbles in a jar) and results of computation.
Grade: 2
Sample Activities:
· Students are asked if a sixty-seat bus will be adequate to take the two first grade classes on their field trip. After it is known that there are 23 children in one class and 27 in the other, individuals volunteer their answers and give a rationale to support their thinking; front end estimation should lead to the conclusion that the total number of students is between 40 and 60. A discussion might be directed to the question of whether an exact answer to the computation was needed for the problem.
· Students are shown a glass jar filled with about eighty marbles and asked to estimate the number in the jar. In small groups, they discuss various approaches to the problem and strategies they can use. Each group shares one strategy with the class, and the estimate that resulted. The teacher makes notes about students' work throughout the activity.
· Second grade students can be challenged to estimate the total number of students in the school. They will need to talk informally about the average number of students in each class, the number of classes in a grade level, and the number of grade levels in the school. They might then use calculators to get an answer, but the result, even though the exact answer to a computation, is still an estimate to the original problem. They discuss why that is so.
· Primary-grade students explore the meanings of comparison words by listening to How Many is Many? by Margaret Tuten. They compare big and small, long and short, a lot and a few. They list how many pieces of candy would be a few and how many pieces would be many, eventually reaching general agreement, perhaps on 5 as a few. Then they consider whether 5 teaspoons of medicine would be a few.
· Given a pair of real-life situations, students determine which situation in the pair is the one for which estimation is a good approach and which is the one that probably requires an exact answer. One such pair, for example, might be: sharing a bag of peanuts among 3 friends and paying for 3 tickets at the movie theater.
· Given a set of cartoons with home-made mathematical captions, first graders decide which of the cartoon characters arrived at exact answers and which got estimates. Two of the cartoons might show an adult and a child looking at a jar of jellybeans and the captions might read: Susie guessed that there were 18 jellybeans left in the jar and Susie's mom counted the 14 jellybeans left in the jar.
· Students read or listen to newspaper headlines and discuss which involve exact numbers and which might be estimates.
Kidspiration Acitivity:
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