math leadership support network ’08-’09. estimation review what is the difference between an...

Math Leadership Support Network ’08-’09


ESTIMATION ESTIMATION ReviewReview

What is the difference What is the difference between an estimate between an estimate and a guess?and a guess?



Why estimate?Why estimate?

When should we When should we estimate?estimate?


Types of ESTIMATION:Types of ESTIMATION:

MeasurementMeasurementQuantityQuantityComputationalComputational


COMPUTATIONAL COMPUTATIONAL ESTIMATION ESTIMATION StrategiesStrategies::

Front-end Front-end ClusteringClustering RoundingRounding Compatible/Nice NumbersCompatible/Nice Numbers Special NumbersSpecial Numbers


Front-end StrategyFront-end Strategy


Front-end Strategy Front-end Strategy with adjustmentswith adjustments


Clustering Strategy

Estimate the total attendance Monday 73,250Tuesday 63,819Wednesday67,490Thursday 73, 180Friday 74, 918Saturday 68, 490


Rounding Strategy


Compatible/Nice Numbers Strategy

3388

Estimate 3388 ÷ 7

a) 3500 ÷ 7 b) 3200 ÷ 7

c) 3200 ÷ 7 d) 3400 ÷ 8

e) 3300 ÷ 7 f) 4000 ÷ 8


Special Numbers Strategy

7/8 + 6/13 =

9.84% of 345 =

436.7 ÷ 0.98 =

103.87 x 24.3 =


WHY????

With all of the great estimation strategies out there, why do our students struggle with computational estimation??

Why do some of our students, work out the original problem and then round for their estimate?



How can we help How can we help students become students become better estimators?better estimators?

How can we assess How can we assess their ability to their ability to estimate?estimate?


Grade-Grade-Level Level

BreakoutsBreakouts


Middle School Middle School BreakoutBreakout COMMIT TO AN OUTCOME:COMMIT TO AN OUTCOME:

Terrence and his group were given Terrence and his group were given

this problem to estimate: this problem to estimate: 48 x 2448 x 24

17 x 5 17 x 5


They each had their own They each had their own method and shared their method and shared their strategies (see chart). strategies (see chart). Donovan said that one of Donovan said that one of the estimates was the estimates was unreasonable. Without unreasonable. Without picking up your pencil or picking up your pencil or calculator, can you quickly calculator, can you quickly spot which approach is spot which approach is unreasonable? Why is it unreasonable? Why is it unreasonable?unreasonable?


EXPOSE BELIEFS:EXPOSE BELIEFS:

Share your choice and reasoning with Share your choice and reasoning with

your group.your group. Ask someone from your group to be Ask someone from your group to be

ready to share the group’s ideas with ready to share the group’s ideas with

the class.the class.


CONFRONT BELIEFS:CONFRONT BELIEFS:

In your group, come up with an agreement on a In your group, come up with an agreement on a good way to estimate this problem. good way to estimate this problem.

Test the proposed methods of estimation from Test the proposed methods of estimation from Terence’s group. Terence’s group.

How does the result of your work compare with How does the result of your work compare with your original thoughts about this problem? your original thoughts about this problem?

Prepare to share your group’s strategy with the Prepare to share your group’s strategy with the class.class.


ACCOMMODATE THE CONCEPTACCOMMODATE THE CONCEPT

Compare your results with those of other groups. Compare your results with those of other groups. Based on what you have observed and heard, Based on what you have observed and heard,

write down the strengths and weaknesses of the write down the strengths and weaknesses of the different approaches used for estimation. different approaches used for estimation.

In your own words, explain an approach to In your own words, explain an approach to estimation that makes the most sense to you and estimation that makes the most sense to you and explain why you chose that approach?explain why you chose that approach?


EXTEND THE CONCEPTEXTEND THE CONCEPT

GO BEYONDGO BEYOND

See HandoutSee Handout


Probes and Probing Probes and Probing Questions…Questions…

What are some types of What are some types of questions you can ask and questions you can ask and activities you can provide to activities you can provide to get at student understanding get at student understanding and/or misconceptions of and/or misconceptions of computational estimation?computational estimation?


1. Which of these 1. Which of these products will be 100 or products will be 100 or greater? How do you greater? How do you know?know? 54.2 x 3.854.2 x 3.8 62.9 x 0.862.9 x 0.8 6.2 x 3.16.2 x 3.1 58.5 x 0.258.5 x 0.2 14.7 x 18.314.7 x 18.3

math leadership support network ’08-’09. estimation review what is the difference between an...

Documents

frontend strategy slide

rounding strategy slide

estimation review

special numbers strategy

types of estimation

terences group

clustering strategy

proposed methods of