# math

/Tag: math

## Tangents – trigonometry – math

By |2018-04-11T09:30:18-07:00July 29th, 2017|Math|

Tangents: This line is tangent to a circle. What is a tangent? A tangent, like a sine or a cosine, is a mathematical way of thinking about a kind of movement that happens in nature. A tangent is really just a rephrasing of the same information we already had for calculating the sine function. Lines and circles [...]

## Sine waves – trigonometry – math

By |2017-07-29T17:59:39-07:00July 29th, 2017|Math|

Sine wave In order to save energy, many, many things in nature move in a kind of repeated pattern we call a sine wave: water waves, sound waves, light waves, electricity, radio waves, and microwaves, for instance. The waves move in one direction quickly, then slow down until they stop, and begin moving [...]

## Trigonometry and triangles

By |2017-07-29T17:52:34-07:00July 29th, 2017|Math|

An infinite distance: stars in the sky Since the time of the Sumerians, about 3000 BC, scientists have studied the stars and the planets. They've tried to figure out the patterns in the movements of the planets. This was much harder because everybody thought that the stars and planets circled around the earth, and really they don't. About 140 BC, [...]

## Cosine – Trigonometry – Math

By |2019-04-26T10:01:02-07:00July 29th, 2017|Math|

Right triangle and cosine What is a cosine? A cosine, like a sine, is a mathematical way of thinking about a kind of movement that happens in nature. A cosine is really just a rephrasing of the same information we already had for calculating the sine function. What's a sine? More trigonometry History of astronomy [...]

## What is zero? Zero and place value

By |2017-07-29T17:35:52-07:00July 29th, 2017|Math|

A math problem showing place value How can you add big numbers without an abacus? You still group the sheep (or whatever) just as you did when you were using the abacus, but now you write the numbers down using place values, so that your hundreds are all underneath your other hundreds, your tens are underneath [...]

## Subtraction – reverse addition!

By |2018-04-24T07:58:27-07:00July 29th, 2017|Math|

A boy walking backwards Subtracting numbers is just the same as adding them, only walking the other way along the number line. To subtract 3 from 8, you start on the number line at 8, and walk backward three steps until you get to 5 - that's the answer: 8 - 3 = 5. Subtraction [...]

## Multiplication and multiplication games

By |2017-07-29T17:30:04-07:00July 29th, 2017|Math|

Walk along a chalk line Multiplying numbers is like jumping along the number line, with all your jumps the same size. It's the same thing as addition, except that you repeat it a certain number of times. So if you are multiplying 4 times 3, it means 3 + 3 + 3 + 3, [...]

## Simple operations – fun with math

By |2017-07-29T17:19:22-07:00July 29th, 2017|Math|

Walk along a chalk line The four basic things you do with numbers are addition, subtraction, multiplication, and division. Each of these is basically a way of describing how fast you are moving along the number line, and in which direction. Find out more about each of these by clicking on them! More about Addition More about Subtraction [...]

## Commutative project – Chalk number line

By |2018-04-24T07:57:26-07:00July 29th, 2017|Math|

Walk along a chalk line To get to understand the number line better, mark out a line on the playground or on the sidewalk outside your house with chalk. At the middle of the line, write 0 (zero). Going one way along the line from zero, write the positive numbers a step apart (1, 2, 3, [...]

## Division – math operation

By |2017-07-29T17:11:41-07:00July 29th, 2017|Math|

How many of these things can I fit into these boxes? Division is a way of answering the question: how many of these things can I fit into that box? If you divide nine by three, that's the same as asking this question: if I have a box that will fit nine things, [...]