Area and circumference of circles

The topic  appears under the 7th Grade Math Mission. This exercise practices the relationship between radius, diameter and circumference in the context of word problems.

Types of Problems
There are two types of problems in this exercise:


 * 1) Find total area of object: This problem uses the area of a circle formula to solve a word problem. The student is asked to find the correct area of an object and insert this in the space provided.Aacoc1.png


 * 1) Use the circumference: This problem uses the circumference of a circle formula to solve a word problem. The student is asked to find the correct circumference and use it to find a solution.Aacoc2.png

Strategies
Knowledge of the four basic circle constants is an advantage on this exercise. Some other formulas arise such as metric unit conversions and area of a rectangle.
 * 1) The circle constants are radius, diameter (which is twice the radius), circumference (which is 2 \pi r or also \pi d) and the area formula (which is \pi r^2, though not needed on this exercise.
 * 2) The circumference formula can be remembered with the mnemonic "Cherry pies are delicious."
 * 3) The area formula can be remembered with the mnemonic "Apple pies are too."
 * 4) All four circle constants can be listed with the acronym CARD.
 * 5) Be careful on the area problem to use the appropriate formulas when more than one is needed.
 * 6) For the Use the circumference problem there is a situation where you need to use the circumference to figure out the distance that a wheel has travelled. Knowledge of the unit conversions is sometimes necessary on this problem.