Parent Primer: Math
When your child is learning about money in math class, you can be generous with advice — after all, you use the stuff every day. But when she asks you to help her pick out which angles are acute, right, or obtuse, you may find yourself acutely aware that matters of geometry make you feel obtuse. We've got the solution to this vexing problem.
So you can help your child with his math homework, we've created a guide with easy-to-understand explanations of math symbols, terms, and concepts from basic math to pre-algebra.
| Symbols to Know | |
| Math Terms | |
| Related to... | Numerals |
| Operations | |
| Graphs, Charts, & Statistics | |
| Shapes | |
| Concepts | |
| Show Me the Shapes | |
| Fractions & Decimals | |
| Symbol | Definition |
| + | Plus; add; and |
| - | Minus; less; subtract; take away |
* or  | Times; multiply |
| / or ÷ | Divided by |
| = | Equals; is equivalent to; |
 | Does not equal; not equal to |
 | Approximately; about equal to; roughly |
| < | Less than |
| > | Greater than |
 | Less than OR equal to |
 | Greater than OR equal to |
| % | Percent; per hundred |
| ° | Degree/s |
 | Square root of |
| ! | Factorial |
| || | Absolute value |
 | Pi |
 | Infinity |
Math Terms
Related to Numerals
Absolute Value - Technically, a number's distance from zero on a number line. An easier way to think of it is the positive value of any number. So the absolute value of -5 is 5. ( |-5|=5.)
Cardinal Numbers - A fancy name for numbers such as 4, 67, etc.
Decimal - A fraction whose denominator is a power of ten (10, 100, 1000, etc.) and written by putting the numerator of that fraction to the right of a decimal point. So, 22/100 is 0.22; .056 is equivalent to 56/1000.
Denominator - The bottom number in a fraction. In 1/2, 2 is the denominator.
Factor - One number is a factor of another number if it can divide into it exactly, i.e. 3 is a factor of 9, or 5 and 11 are factors of 55.
Fraction - A number that represents some part of a whole and written a/b. So 1/2 means 1 of 2 parts, or one-half of something.
Improper fraction - A fraction bigger than 1, such as 3/2 or 9/4.
Integers - All the whole numbers plus all their negative counterparts (-1,-2,-3). Does not include fractions or mixed numbers.
Mixed Number - A number that contains both an integer and a fraction, such as 2 1/2 or 3 1/3.
Multiple - The product of a given whole number and another whole number. On times tables, each number will list its multiples beneath it - i.e. the multiples of 6 are 12, 18, 24, 30, 36, 42, etc.
Negative Numbers - Any number less than zero.
Numerals - A fancy word for numbers.
Numerator - The top number in a fraction. In 1/2, 1 is the numerator.
Ordinal Numbers - A number that indicates order or position, such as 1st, 3rd, 27th, etc.
Percent - Means per hundred and shows the ratio of a number to 100.
Place Value - Where a single number is placed in a larger figure tells you it's value: whether that number stands for the number of tens, hundreds, thousands, etc.
So, in the number 3,245,093.2...
| Millions | Hundred | Ten thousands | Thou- sands | Hundreds | Tens | Ones |
| 3 | 2 | 4 | 5 | 0 | 9 | 3 |
You can see there are 3 millions, 2 hundred thousands, and so on. The 5 is in the thousands place.
Prime Number - Any number that can only be divided by 1 and itself.
Whole Numbers - All the positive numbers and zero - the counting numbers (0,1,2,3...). Does not include fractions or mixed numbers.
Dividend - The number to be divided in a division operation. In the problem, 60÷4, 60 is the dividend.
Divisor - The number that's doing the dividing in a division problem. In the operation, 60÷4, 4 is the divisor.
Equation - A mathematical statement that says two amounts or expressions have the same value; Any number sentence with an 'equals' sign (2+3=6-1).
Exponent - In the number 4³, the 3 on top is called an exponent. It indicates that 4 is being raised to the power of 3, or multiplied by itself 3 times.
Expression - Each part of any number sentence that combines numbers and operation signs (+,-,*, /) is an expression; a number sentence without an equals sign.
Factorial - Any number factorial (written 3! Or 15!) means that you multiply that number by all the whole numbers less than that number. So 6! means 6*5*4*3*2*1.
Inequality - a mathematical statement that says that two quantities are not equal. A number sentence with >,<, or .
Inverse - Related but opposite operations or numbers are inverses of one another. Addition and subtraction are inverse operations. 3 is the inverse of 1/3.
Operation - Adding, subtracting, multiplying, or dividing two or more numbers.
Parentheses - Used to show which operation to perform first. For example, in (2+3)*4, you would first add 2+3 and then multiply that sum by 4.
Power - If you multiply a number by itself, the number of times you multiply it is called a power. For example, 4*4*4 is 4 raised to the third power. It is written 4³.
Product - The result of multiplying two numbers together. Instead of asking, "What is 3 times 4?" The question might be phrased, "What is the product of 3 and 4?" (The answer is 12 for both.)
Quotient - The number that results from a division problem, not including the remainder. In the problem, 60÷4, the quotient is 15.
Remainder - A number 'left over' from a long division problem. In the problem, 61÷4, the answer is 15 with a remainder of 1, or 1r.
Related to Graphs, Charts, & Statistics
Data - A set of information. For example, all the answers collected for a survey would be the data for that survey.
Impossible Number - A number that while it's the correct result of an average, it has an impossible real-world value, i.e. the average family has 2.5 children, but you can't have .5 of a person.
Mean - The average of a group of two or more amounts. To get the mean or average, add the numbers, then divide the result by the number of amounts you summed. Simply, the mean of 3, 15, and 21 is 3+15+21 divided by 3, which is 13.
Median - The number in the exact middle of a set of numbers. So, in the set: 1,3,4,6,13,15,21 - 6 is the median of the set.
Venn Diagrams - Used to show relationships among two or more groups or sets of things. For example:
Area - The amount in square units contained in a two-dimensional shape or surface.
Circumference - The distance around a circle.
Closed Curve Shapes - A plane shape made with curved lines, like a circle or oval.
Congruent figures - Figures that are the same shape and the same size. They can be rotated or flipped and still be congruent.
Diameter - Any line that passes through the center of a circle that joins two points on the circle; Twice the radius.
Geometry - Math related to shapes and figures such as area, size, volume, and length.
Line - A straight set of points that extends infinitely in both directions.
Line Segment - A part of a line with a beginning point and an end point.
Perimeter - The distance around a polygon; the sum of the lengths of the sides of a two-dimensional figure.
Plane shape - A two-dimensional or flat shape.
Polygon - A plane shape with 3 or more straight sides (line segments), like a triangle, hexagon, or rectangle. For examples, see Show Me the Shapes.
Radius - The distance from the center of the circle to any point on it; Half the diameter.
Ray - A part of a line that has one end point and continues infinitely in one direction.
Solid Shape - A three-dimensional shape, such as a cube, sphere, cone, or pyramid.
Tessellations - Using a single shape repeatedly to make a larger pattern or mosaic.
Geometry is all about shapes and lines, so a picture is worth more than a thousand words in the case of defining geometric vocabulary. It's better to show than tell in the case of shapes. For example, 
The point where those two rays meet is called the vertex - the point where sides meet in a shape or figure.
Angles
An angle is the distance between two rays or two line segments. Three kinds of angles you will encounter are:
 |  |  |
| Acute Angle | Right Angle | Obtuse Angle |
| A positive angle measuring less than 90 degrees | An angle of exactly 90 degrees. Indicated in pictures as a square | An angle whose measure is greater than 90 degrees |
Triangles
Three general types of triangles:
 |  |  |
| Scalene Triangle | Isoceles Triangle | Equilateral Triangle |
| A triangle with no sides of the same length | A triangle with two sides of the same length | A triangle where all the sides (and angles) are the same length |
And one special one, a Right Triangle, which is any triangle containing a right angle:
 |
|
Polygons
 |  |  |
| Parallelogram | Rhombus | Trapezoid |
| A 4-sided plane shape with 2 pairs of parallel sides of equal length | A parallelogram with 4 sides of the same length | A 4-sided plane shape with 1 pair of parallel sides |
Fractions & Decimals
Fractions: General
First things first. Fractions are a lot easier to work with if you first reduce them to their simplest form, which means that 1 is the only number that can divide evenly (meaning without a remainder) into the numeration and denominator.
For example: 330/550
We can see right away that both numbers can be divided by 10, reducing the fraction to
33/55
Both top and bottom can also be divided by 11, giving us the equivalent fraction
3/5
Neither of these numbers has any common factors, so 3/5 is the simplest form.
Another way to do this would be to find the greatest common multiple of 330 and 550, which is 110. This allows you to reduce the fraction in one step.
Fractions: Operations
To add or subtract fractions with the same denominator, simply add or subtract the numerators of those fractions.
3/5 + 1/5 = 4/5
4/7 - 2/7 = 2/7
If the fractions have different denominators, you must convert them to fractions with the same denominator. To do this, find the smallest common multiple of both numbers and convert both fractions to ones with that multiple as the denominator:
3/5 + 3/4 The smallest multiple of 5 and 4 is 20
(3/5 * 4/4) + (3/4 * 5/5)
12/20 + 15/20 = 37/20 or 1 17/20
To multiply fractions, simply multiply the numerators and denominators:
1/3 * 4/9 = 1 * 4/3 * 9 = 4/27
To divide by a fraction, such as:
4 ÷ 1/4
Simply flip the fraction (which is the divisor) and multiply by that number like so:
4 * 4/1 (or 3) = 16
Another way to think of it is, "How many ¼'s would fit into 4?" Or how many quarters make up 4 dollars. Any way you look at it, the answer is 16.
Turning Fractions into Decimals
To convert a fraction into a decimal, simply divide the denominator into the numerator. So ¼ = 1 ÷ 4 = 0.25
Decimals: Operations
Adding and subtracting decimals is no different than with whole numbers. You just line up the decimal points and perform the operation. It only gets tricky when you multiply or divide.
When you multiply decimals, line up the numbers on the right (not with the decimal points) and multiply as you normally would:
23.21
* 4.2
---------
97482
then place the decimal point in the product by adding up how many numbers in the original are to the right of the decimal point.
23.21 (2 numbers two the right of the decimal or 2 decimal places)
* 4.2 (1 number two the right of the decimal or 1 decimal place)
---------
97.482 (3 numbers to the right of the decimal or 3 decimal places)
So the answer is 97.482
When you divide decimals...
_____
2.4 /48.96
If the divisor contains a decimal, get rid of it! Move the decimal place over an equal amount in both numbers until the divisor is a whole number (multiply both the divisor and the dividend by whatever power of ten is necessary to get rid of the decimal).
_____
24 / 489.6
Then perform the division as you normally would. The decimal point moves up into the answer at exactly the same point as it is in the dividend:
_20.4_
24 /489.6
LESSON PLAN
