# Finding perimeter when a side length is missing | Math | 3rd grade | Khan Academy

## By Khan Academy

Lindsay finds the perimeter of a figure when a side length is not given.  # Introduction to perimeter

## By Khan Academy

Find perimeter by adding side-lengths of various figures.  # Perimeter 2

## By Khan Academy

Find perimeter by adding side-lengths of various figures.  # Finding perimeter

## By Khan Academy

Find perimeter by adding side-lengths of various figures.  # Identifying proportional relationships

## By Khan Academy

Is the perimeter of a square proportional to the side length of the square?  # Grade 3 Math Perimeter 3 MD 8

## By EngageNY

Solve real world problems involving perimeters of polygons, including finding the perimeter given the side lengths and finding an unknown side length  # Estimating Products | MathHelp.com

## By MathHelp.com

This lesson covers perimeter. Students learn that the perimeter of a figure is the distance around the figure, so the perimeter of a figure can be found by adding the lengths of its sides. Since all four sides of a square are equal in length, the perimeter of a square that has a side with a length of 8 feet is 8 + 8 + 8 + 8, or 32 feet. Since opposite sides of a rectangle are equal in length, the perimeter of a rectangle that is 4.5 meters by 6.2 meters is 4.5 + 4.5 + 6.2 + 6.2, or 21.4 meters.  # Math Antics - Perimeter

## By mathantics  # Perimeter | MathHelp.com

## By MathHelp.com

This lesson covers naming angles. Students learn the definition of an angle and the concept of measure, including the following vocabulary: side, vertex, protractor, degrees, right angle, acute angle, obtuse angle, and straight angle. Students also learn what assumptions can and cannot be made from a given figure.  # Surface Area of a Pyramid | MathHelp.com

## By MathHelp.com

This lesson covers the definition of perpendicular lines. Students learn the definition of perpendicular lines and use algebra to find the measures of angles in problems that involve perpendicular lines. Students are also asked to determine whether given information is sufficient to determine if two lines are perpendicular.  # Measurement - Perimeter made easy!

## By tecmath  # Perimeter Word Problems | MathHelp.com

## By MathHelp.com

This lesson covers the area of a trapezoid. Students learn that a trapezoid is a quadrilateral with one pair of parallel sides, and the formula for the area of a trapezoid is 1/2 times (base 1 + base 2) times height. For example, the area of a trapezoid that has bases of 10 centimeters and 12 centimeters and a height of 8 centimeters is 1/2 times (10 + 12) times 8, which simplifies to 1/2 times 22 times 8, or 11 times 8, which is 88 square centimeters.  # Area perimeter and volume of rectangle

## By tecmath  # Geometry Introduction - Basic Overview - Review For SAT, ACT, EOC, Midterm Final Exam

## By The Organic Chemistry Tutor  ## By McCarthy Math Academy

With a little help from the group, Mindless Behavior, I have created a math video with lyrics to help my students to understand and apply core math skills for third grade. People of all ages can jam out to this one. Enjoy!

I've got a case of the operation blues.
Because I don't know which one I should use.
Look at the word problem for the clues.
The key words tell you how to choose.

Each means you multiply or you must divide.
Tryna find the total? Then you multiply
Total's in the problem? Then you must divide.
Not quick to solve it, draw it, get it right.

Addition's easy for me and you
Sum, In all, together, and total too.
When do you subtract? How many more?
Fewer? Left? Less? Difference in a score?

Place value's next. Disco on the " dess "
Ones, tens, hundreds, to the left
Thousands, Ten thousands, hundred...thousand
Say the name of the place, yeah.

The value's the amount of the place
For example, 2,060.
The value of the 2 is 2-0-0-0,
The value of the 6 is 6-0.

When you round, find and underline the place
Spotlight to the right, decide the digit's fate
5 or more, add 1 to the rounding place
4 or less, do nothing but walk away, (estimate)

A pen, penny is one, one cent
A Nic-kel is five, a dime is ten cents
25 for a quarter, George Washington
100 cents makes a dollar, there he goes again.

For pictographs, you gotta check out the key
One smiley face might really equal three
For bar graphs, pay attention to the scale
Think it's counting by ones, huh, you'll fail

Fractions are easy, just draw your best.
Here they go from least to greatest
1/12, 1/6, Â¼, 1/3,
Â½, 2/3, Â¾, Fraction nerd!

You see that number on top,
That's called the numerator
It describes the amount
That is being considered
And if you jump down from the fraction bar
Denominator
It's the total number of equal parts.

Let me give you an example:
Leslie Moin has some coins
A total of 9
2 happen to be pennies
While 7 are dimes.
What's the fraction of dimes?
How many coins? 9
How many dimes? 7
Say the fraction -- seven ninths

Length times width is Area
Distance around is Perimeter
Break down the GEOMETRY

3 sides makes triangle
5 pentagon, 6 hexagon
8 octagon, 10 decagon

Lines that never cross - PARALLEL
Lines that meet or cross - INTERSECTING
Lines that form right angles -- PERPENDICULAR

Same shape, same size -- CONGRUENT
Line that cuts in half - SYMMETRY
Up and Down - VERTICAL
Left to Right -- HORIZONTAL

An angle less than right - ACUTE
An angle opened wide - OBTUSE
Ninety degrees square corner - RIGHT ANGLE

Back to triangles
3 sides the same = equilateral
2 sides the same = isosceles
no sides the same = Hey, that's a scalene right!

So, that's it.
That's our math song.
Before we leave,
That way you know what the problem
Don't be lazy, be brilliant.
Piece! Like a fraction.  # Math Antics - Area

## By mathantics  # What Is A Fractal (and what are they good for)?

## By MITK12Videos  # Polygons in the Coordinate Plane

## By Anywhere Math  ## By

2nd Grade math is fun with these learning videos! Each lesson can help students with word problems, math games or help prepare for a test! Great for a review of 2nd grade or for an introduction!  # Learn XY Coordinate Plane, Graphing Points, Lines & Distance - [5-9-15]

## By Math and Science

Quality Math And Science Videos that feature step-by-step example problems!   