2nd Grade - Make Estimates When Measuring

 
     
 
     
 
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2nd
Fractions
Make Estimates When Measuring
Recognize when an estimate is reasonable in measurements (e.g., closest inch).
Check subtraction and addition problems using estimation. Round numbers to the nearest hundred.
 

Sample Problems

(1)

To estimate means to _______________________________.


(to find the approximate calculation of quantity)

(2)

Solve the problem. Estimate to check your answer.


Solve Check


242

+315 +_______


(3)

Read the story problem and solve. Estimate to check your work.

 

Tara’s family traveled 279 miles to get to the beach. From the beach her family traveled another 129 miles to visit her grandmother. How many miles did Tara’s family travel.

 

Solve Check

 

(4)

Use the number line to solve problems 7-12.


700 710 720 730 740 750 760 770 780 790 800

I_____I____I____I____I_____I_____I____I_____I_____I_____I


709 is closer to ___________.


(5)

Find an object like the one shown in the picture. Estimate in inches the length of the object. Then use a ruler to measure.

 spoon

Estimate: about ___________inches

 

Measure: about ___________ inches

 

Learning Tips

(1)

Rounding is reducing the digits in a number while trying to keep the value similar. Rounding is less accurate, but makes it easier for your child to add and subtract digits in a timelier manner. (Ex. When rounding the number 121 to the nearest hundred think, is the number 121 closer to 100 or 200. It is closer to 100; therefore the number 121 is rounded to the number 121.) When helping your child to round numbers have your child decide which is the last number to keep. Increase the number by 1 if the next digit is five or more. This is called rounding up. Leave the number the same if the next digit is less than five. This is called rounding down. Estimation is the approximate calculation of quantity. Remind your child that when he/she estimates, to use the word “about” to show that the answer is an estimate.

(2)

Help your child better understand the concept of estimating by completing a fun activity with your child. Take an empty clear container or glass jar and fill the container with many of one object. This can be a type of candy, beans, pennies, beads, or any other small item. Have your child estimate (give an educated guess) as to how many items are in the jar. Your child may want to write his/her estimate down on a small piece of paper. After your child has given his/her answer, empty out the container and guide your child to count the items. Remind your child to separate each item from the groups of items using his/her finger while counting. After counting, discuss with your child whole close his/her estimate was. Continue to complete this activity again and again using different items in the container.

(3)

When measuring using a ruler, remind your child to take his/her time in order to get an accurate measurement. Show him/her how to align the left end of the ruler to the one end of the object being measured. Encourage your child to check their answer again to make sure that it is accurate. Many second graders round their answer to the nearest whole number on the ruler. If the object being measured ends between the 3 inch and 4 inch mark on the ruler, but is closer to the 3, encourage your child to round the measurement to say that the object is about 3 inches long.

(4)

If your child is having trouble deciding to round up or down, encourage your child to use a number line when rounding to find an estimate to an addition or subtraction problem. (Use the following website to create number lines that will assist your child when rounding http://themathworksheetsite.com/numline.html.) Have him/her use a marker (coin, bean, two-sided chip) to find the number on the number line. Once the number is located, ask your child to find the number that the marker is closest to. For example if the number being rounded was 181, encourage your child to put the marker about where the number 181 would be located on the number line. Ask your child if the marker is closer to the number 100 or 200. Your child should see that the marker is closer to the number 200; therefore, the number 181 is rounded up to the number 200.

(5)

To help your child better understand rounding and estimation, tell your child that he/she is going to round numbers to the nearest hundred. Say “We are going to round numbers between 100 and 200.” Give your child a number and have him/her tell you if that number would be rounded to 100 or 200. For example, you might use the number 199. Your child would say that 199 is closer to 200. Repeat this game allowing your child to think of numbers as well.

Extra Help Problems

(1)

Solve the problem. Estimate to check your answer.


Solve Check


242

+315 +_______


(2)

Solve the problem. Estimate to check your answer.


Solve Check


242

+315 +_______


(3)

Read the story problem and solve. Estimate to check your work.

 

Tara’s family traveled 279 miles to get to the beach. From the beach her family traveled another 129 miles to visit her grandmother. How many miles did Tara’s family travel.

 

Solve Check

 

(4)

Read the story problem and solve. Estimate to check your work.

 

Cara baked 184 cookies. Tammy baked 95 cookies. How many more cookies did Cara bake than Tammy?

 

Solve Check

 

-

_________

 

(5)

Estimate. Then solve the problem.


284

+ 145 Estimate ______________


Solve ______________


(6)

Tara said that 359 + 148 = 590. Use estimation to check her answer.


Estimate



-_________



(7)

Use the number line to solve problems 7-12.


700 710 720 730 740 750 760 770 780 790 800

I_____I____I____I____I_____I_____I____I_____I_____I_____I


709 is closer to ___________.


(8)

775 is closer to ___________.


(9)

755 is closer to ___________.


(10)

The number 715 is between __________ and __________.


(11)

Circle the best answer.


The number 765 is between which two hundreds.


  1. 200-300

  2. 700-800

  3. 800-900


(12)

Circle the best answer.

 

737 is closer to _______________.

 

700       or      800


 

(13)

Place the numbers below in order on the number line.


I_____I____I____I____I_____I_____I____I_____I_____I_____I



810 850 890 900 840 800


820 880 830 860 870


(14)

What number is half way between 700 and 800 on the number line?


700 710 720 730 740 750 760 770 780 790 800

I_____I____I____I____I_____I_____I____I_____I_____I_____I


(15)

Estimate how many Xs are in the space below. Write your estimate on the line before.


X X X X X X X X X X

X X X X X X X X X X XX XXXXXX

X X X X X X X X X X X X X X X X X X X

X XX XXXXXX XXXXXX X XXX X X X


_____________


(16)

Use a ruler to measure the line in inches. Write the answer on the line.


________________________________________

________ in.


(17)

About how many inches or feet would the real object be? Circle the best answer.



7 inches


7 feet


(18)

Find an object like the one shown in the picture. Estimate in inches the length of the object. Then use a ruler to measure.

 

 picture frame

Estimate: about ___________inches

 

Measure: about ___________ inches

 

 

(19)

Find an object like the one shown in the picture. Estimate in centimeters the length of the object. Then use a ruler to measure.

 

 pencil

 

 

Estimate: about ____________ centimeters

 

Measure: about ____________ centimeters

 

(20)

Circle the answer.

 

About how many days are there in a month?

 

A. 7   B. 31   C. 60   D. 365

 

(21)

Circle the activity that would take about 1 day.


A trip to the zoo Brushing your teeth


(22)

Decide the amount of time each activity takes. Draw a line to match the activity with the amount of time.


Brushing your teeth about 5 hours


Going on vacation about 5 minutes


Going to school about 5 days


(23)

Circle the activity that takes about the same amount of time.


Eating breakfast Painting a house Drawing a picture


(24)

Underline the activities that take about 1 minute.


Taking a picture Blowing up a balloon Watching a movie


(25)

To estimate means to _______________________________.


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