7th Grade PreAlgebra: Help with Area and Volume
By the end of 7th grade, you'll have learned to calculate area for most 2dimensional shapes, as well as surface area and volume for regular 3dimensional shapes. Keep reading for information about the relevant formulas.
Area and Volume for 7th Graders
Students usually learn about area and volume in geometry class, but these can also be considered prealgebra skills because they require you to solve for a variable. For instance, if you're finding the area of a rectangle, you'll solve the equation A = length x width for the variable 'A.' Alternatively, you might be asked to solve for the rectangle's length when given its area and its width.
Area and Surface Area
Many 7th graders have already learned the area formulas for most 2dimensional shapes, but some schools introduce the formula for the area of a circle in 7th grade. The formula is A = (pi)r^2, where 'r' is the radius (half the diameter), and the value of 'pi' is 3.14.
The surface area for any regular, 3dimensional object, like a cylinder or rectangular prism, is equal to the sum of the areas of its surfaces. For instance, a rectangular prism has two smaller bases and four larger sides. To find the total surface area, add together the areas of the two small bases. Then, add the sum of the areas of the four large bases. Here's one common way to write this formula, where 'l' is length, 'w' is width and 'h' is height:
V = 2(l x w) + 2(l x h) + 2(w x h)
Volume
A regular, 3dimensional object's volume is the product of the area of its base and its height. Returning to the rectangular prism example in the last section, you would multiply the area of one of the small bases by the height of the prism to get its volume. This formula can be written as V = l x w x h, since the area of the base is equal to length times width (l x w). For a cube, the formula is V = s^3, where 's' is the length of a side.
To find the volume of a cylinder, calculate the area of the circular base using the formula given in the first section, A = (pi)r^2. Then, multiply this by the height of the cylinder, 'h.' Putting this all together, the formula is V = (pi)r^2 * h.
The volume of a triangular prism is the product of the prism's height, 'h,' and the area of its base (V = Height * Area of the Base). You can find the area of the prism's triangular base using the formula A = 1/2 * b * h, where 'b' is the base of the triangle and 'h' is its height. Be careful not to confuse the height of the triangle with the height of the prism, or the area of the prism's base with the length of the triangle's base.
Other Articles You May Be Interested In

Detailed resumes, biographical DVDs, polished essays and nervous waiting. Fortunately, there's 'Sesame Street' to pass the nervous hours while waiting expectantly for an acceptance letter. This isn't college admissions, or even elite high school admissions. It's preschool, where the competition in several large cities has grown...

Finding and taking advantages of resources to help with homework is an important skill that students will use throughout their academic careers. Read on to learn more.
We Found 7 Tutors You Might Be Interested In
Huntington Learning
 What Huntington Learning offers:
 Online and incenter tutoring
 One on one tutoring
 Every Huntington tutor is certified and trained extensively on the most effective teaching methods
K12
 What K12 offers:
 Online tutoring
 Has a strong and effective partnership with public and private schools
 AdvancEDaccredited corporation meeting the highest standards of educational management
Kaplan Kids
 What Kaplan Kids offers:
 Online tutoring
 Customized learning plans
 RealTime Progress Reports track your child's progress
Kumon
 What Kumon offers:
 Incenter tutoring
 Individualized programs for your child
 Helps your child develop the skills and study habits needed to improve their academic performance
Sylvan Learning
 What Sylvan Learning offers:
 Online and incenter tutoring
 Sylvan tutors are certified teachers who provide personalized instruction
 Regular assessment and progress reports
Tutor Doctor
 What Tutor Doctor offers:
 InHome tutoring
 One on one attention by the tutor
 Develops personlized programs by working with your child's existing homework
TutorVista
 What TutorVista offers:
 Online tutoring
 Student works oneonone with a professional tutor
 Using the virtual whiteboard workspace to share problems, solutions and explanations