LEARNING TARGET

Estimate sums and diferences using decimals and fractions. 

EXAMPLE PROBLEM 

12.34 + 45.78=

12 + 46=58

LESSON 

TO ESTIMATE A SUM, YOU ROUND EACH NUMBER TO THE NEAREST WHOLE NUMBER THEN ADD ALL OF THE NUMBERS UP TO GET THE SUM.

TO ESTIMATE A DIFFERENCE, YOU ROUND ALL OF THE NUMBERS TO THE NEAREST WHOLE AND SUBTRACT THEM TO GET THE DIFFERENCE.

 EXAMPLE OF DECIMAL

THIS IS PI

Learning Target:

The learning target for this lesson is, using strategies to develop formulas for finding the circumference of circles.

Example Problem:

If you measure the diameter and the circumference of a circle you can calculate pi. Pi is equal to the circumference divided by the diameter. This is true for all circle figures.

If the diameter of the shape is 15 centimeters and you want to find the circumference, you would do the equation 15 times pi(which is equal to 3.14 roughly). So the solution to the equation would be 47.1 centimeters, that is the circumference.

Lesson:

The circumference of a circle is the distance  around it. The diameter is the distance across the circle at its widest point. The ratio of the circumference and the diameter is always the same for every circle. This ratio is called pi (which is equal to 3.14). If you know the diameter of a circle, you can multiply it by pi to find the circumference. On the other hand, if you know the circumference you can divide it by pi to get the diameter.

Check out these cool activities:

  http://www.aaamath.com/geo612-circumference-circle.html#pgtp

http://www.bbc.co.uk/scotland/education/bitesize/standard/mathsI/area/circim_circle_rev2.shtml

http://www.mathgoodies.com/lessons/vol2/circumference.html

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Modified on October 23, 2006 at 7:06 PM