# Hot Education How-Tos

### How To: Build a Tesla coil

Video showing the construction of a typical spark-gap type Tesla Coil. There was a lot of information and I couldn't cover everything in this video. So there will be more in a part 2a and 2b.

### How To: Build a Simple Paper Bridge as a Science Experiment

Every day we pass bridges, whether it's a foot bridge, a highway overpass, a span over water, or a viaduct over a valley. We pass on these structures without even thinking of the engineering genius that went into their design and construction, let alone the science behind their strength.

### How To: Write A Letter From Teachers To Parents

Parental involvement is a crucial ingredient in the success of many children. Teachers know the saying all too well that it takes more than a village to raise a child, for one - it takes parental involvement. Thus, it is important for teachers to reach out to parents in that first week of school. Teachers should write a formal letter that is welcoming and easily comprehensible to the parent and the student. This letter should be able to communicate that the teacher values the child’s educatio...

### How To: Write a slope-intercept equation given an X-Y table

In this tutorial the author shows how to derive a slope-intercept equation of a line given an X-Y table. He explains that the general form of slope intercept form which is y = m*x + b. Now he intends to find value of slope, i.e. m first. Now slope is change in y over change in x. He computes the slope using the X-Y values from the table. Next he substitutes a pair of x, y value in the equation to compute the value of y intercept b. Now finally substituting the values in the equation the slop-...

### How To: Find a slope of a straight line with: Ax + By + C = 0

In this video the instructor shows how to find the slope of an equation which is in the form Ax + By + C = 0. He says that the formula to find the slope of a line in the above form is slope m = -A/B, where A and B are the numeric constants of the variables x and y in the given equation. He goes on and further shows how to do this with a couple of examples. He shows how to reduce any equation into the general form and how to apply the slope formula then. This video shows how to find the slope ...

### How To: Make hydrochloric acid from salt

In this tutorial, we learn how to make hydrochloric acid from salt. First, you will pour some salt into a distil flask. After this, you will add in some concentrated sulfuric acid to the salt. Next, you will let these react with each other. You will start to see gasses bubble up and the excess hydrogen chloride gas come out through the top of the tube. To create a stronger reaction, you can add heat underneath the reaction. Then, test this by exposing it to ammonium chloride. If it's the righ...

### How To: Remember "greater than" & "less than" symbols

This video shows you how to easily remember "greater than" and "less than" math symbols. The first thing you have to remember is that "less than" symbol looks like the letter L ("less than" symbol is "<"). When you see this sign, remember that < looks like L and means "less than". The other symbol, "greater than" does not look like the letter L, therefore it cannot be "less than" and it's easier to remember. The "greater than" symbol is ">". That's it! Good Luck!

### How To: Find the area of a triangle when given 2 sides & angle

This video shows you how to easily find the area of a triangle when you know the length of 2 sides and the angle between them. The first thing you have to do is mark the sides of the triangle by a, b, c, where a is the side between A and B, b is the side between B and C and c is the side between C and A. If you know 2 of these 3 sides an you know the angle between them you can find the area of the triangle very simple: Area= (a x b x sin c)/2, where a, b are the two sides and c is the angle b...

### How To: Solve equations with the order of operations

In mathematics, the order of operations define the priority in which complex equations are solved. The top priority is your parenthesis, then exponents, followed by multiplication and division, and finally addition and subtraction (PEMDAS). This video tutorial demonstrates the order of operation with various examples and explains the associated methodology. From Ramanujan to calculus co-creator Gottfried Leibniz, many of the world's best and brightest mathematical minds have belonged to autod...

### How To: Find and sketch the domain of a multivariable function

Looking for a primer on how to find and sketch the domain of a function z = f(x, y) in calculus? Learn how with this free video calc lesson. From Ramanujan to calculus co-creator Gottfried Leibniz, many of the world's best and brightest mathematical minds have belonged to autodidacts. And, thanks to the Internet, it's easier than ever to follow in their footsteps (or just finish your homework or study for that next big test).

### How To: Identify characteristics of a sample during a survey

To identify characteristics of a sample in your survey, there are many factors to consider of your samples. The first four characteristics you need to focus on are gender, age, income level, and education level. All four of these characteristics must be proportional to that of the population. You also need to consider the geographic location. Only take samples from the immediate geographical area. Finally, an important characteristic of the survey is the sample size. You do not want to ask to...

### How To: Find the 100th term in a sequence

Need to find the nth term in a given arithmetic sequence? See how it's done with this free video math lesson. Need help finding the From Ramanujan to calculus co-creator Gottfried Leibniz, many of the world's best and brightest mathematical minds have belonged to autodidacts. And, thanks to the Internet, it's easier than ever to follow in their footsteps (or just finish your homework or study for that next big test). With this installment from Internet pedagogical superstar Salman Khan's seri...

### How To: Make nitric acid

Watch this science video tutorial from Nurd Rage on how to make nitric acid. They show three ways to make nitric acid based on two different chemical approaches, both of which can be done using easily accessible materials.

### How To: Calculate percent composition for chemistry

To calculate percentage composition we will take the example CO2 it stands for Carbon-Di-Oxide. It is the composition of Carbon and Oxygen. We have one carbon and its weight is 12.01 and 2 oxygen. So, we will multiply 2 with 16.00 which is the weight of the oxygen.

### How To: Make Your Own Homemade Glow Sticks

Glow sticks, a popular favor at parties and outdoor events, and a must-have on Halloween, can be traced back to the United States Navy in the mid-1960s. The military desired improved visibility during night operations, and glow sticks, with their small-size portability and lack of batteries, were a perfect tactical solution.

### How To: Find a missing coordinate given: coordinate & equation

In this video, the instructor shows how to find an unknown coordinate given the other coordinate of that point and the equation that passes thought the point. A point is said to lie on the graph, if the point can satisfy that equation of the line. To check if a particular point satisfies an equation, all you have to do is substitute the value of the point in that equation and check if it validates the equation. Now, substitute the given point with an unknown coordinate in that equation. If th...

### How To: Cite a website with hard to find author or date info

Sometimes it can be difficult to find information essential to a citation on a webpage, like an author or a date. Here are some steps you can take to make up for this lack of information.

### How To: Make a crazy foam explosion science experiment

Check out this video to see our Fantastic Foamy Fountain in action. The experiment uses Hydrogen peroxide and dry yeast. Hydrogen peroxide is similar to water but it has an extra oxygen atom. This makes it more dangerous and only adults should handle the hydrogen peroxide.

### How To: Determine the age of a fossil using carbon-14

If you have a fossil, you can tell how old it is by the carbon 14 dating method. This is a formula which helps you to date a fossil by its carbon. If a fossil contains 60% of its original carbon, how old is the fossil? The half life of carbon 14 is 5600 years. That means this is how long it takes for half the nuclei to decay. After 5600 years, if we start with a gram, we end up with half a gram. This rather complex formula shows you how to solve this puzzle using accepted scientific methods.

### How To: Solve for the missing ratios or proportions

In this video the tutor shows how to solve the missing ratios or proportions. He explains it with an example, where a number in one of the ratios is missing and he intends to find this value. He shows the example of cross multiplication, where you multiply the values on the either side of the equation diagonally and finally solves the equation which results in the value of the unknown value. This is an introductory video explaining how to use rations and proportions to find missing values.

### How To: Translate a sentence into math symbols

We will be translating the sentence "twice y differs from 5 by more than two, “into a mathematical equation. The word twice generally means two times, so 2*y (because y comes next in the sentence). Differs normally means is different and a difference from something in a mathematical sentence means subtraction most of the time, thus minus five. We don't know if we’re talking about below 5 or above 5 on the number line, so we put absolute value around the equation. More than implies a greater t...

### How To: Make a Monster Dry Ice Bubble

Sure it's been done before, but it never gets old. There's something magical about dry ice, bubbles, and especially the result you see when they're combined!

### How To: Make Vitriol (Sulfuric Acid) Using the Oxidizing & Electrochemical Methods

If you've been following the news lately, you've probably heard of the word "vitriol" being used as a political weapon, with people like celebrity left-winger Jane Fonda blaming conservatives like Sarah Palin for "vitriolic" attacks on Democrats and the "violence-provoking rhetoric of the Tea Party" movement for the recent Arizona shooting.

### How To: Find the coordinate of a point

In this video the author shows how to plot a point on the coordinate plane. He explains about the coordinate plane and shows how to read and write points to it with an example. He says that any point on the coordinate plane has an x, y- coordinate values. He says that for any point its projection on the x-axis is its x-coordinate and the points projection on y-axis is its y-coordinate. He shows how to find this out for a sample value and plots the coordinates of it. In this video the author u...

### How To: Multiply & Divide Numbers (Basic Elementary Math)

Adding and subtracting may be the easiest of mathematical operations, but once you get it down, multiplication and division can be just as easy. That's why it's called elementary arithmetic. If it were harder, it would be called college algebra or trigonometry. But it's not— it's basic math, and once you get your head around the numbers, you'll never hate math class again! (Okay, maybe you will.)

### How To: Make Soap Out of Guava Leaf Extract for a Science Investigatory Project

Unless you're a high-schooler building a nuclear fusion reactor, the hardest part of a science investigatory project often is coming up with a good idea. You want it to be cool yet feasible, novel but still useful.

### How To: Determine the density of salt water

Everyone floats in the Dead Sea because the amount of salt in water effects the density. Do a hands-on experiment and practice checking density. Here’s a good science experiment to do in class or at home, if you have access to an electronic balance.

### How To: Be a human calculator

Before we had the calculator and before we had the abacus we had the human brain to complete our math problems for us. Remember that? Well, it seems that few of us do, resorting to calculators on our phone for elementary subtraction problems and multiplication.

### How To: Learn Calculus in 20 minutes

Did you sleep all semester in your Calculus class? Are you just waking up now to realize you have a test on Monday and that you're totally screwed? Well, luckily you can learn an entire semester worth of Calculus in just twenty minutes... or at leasts that's the hope.

### How To: Calculate azimuth in trigonometry

Azimuth is simply the angle of an object in the sky along the horizon. Yes, it's spherical trigonometry but it's not difficult! Check out this video and in just a few minutes you will be able to solve azimuth problems on your own.

### How To: Make This Amazing 9-Layer Density Tower from Things Found in Your Kitchen

Ralph Waldo Emerson once observed that "the seed of science" was "wonder," and taking a look at this nine-layer liquid tower from Steve Spangler's Sick Science! channel, one can't help but do just that — wonder. How is this possible? Is this magic or what?

### How To: Make a Paper Plate Speaker That Actually Works for Under $1

Back in 2007, YouTube user HouseholdHacker posted a parody video on how to make a high-def speaker for under a buck. MythBusters took on the challenge and busted it.

### How To: Make DIY Nitrogen Triiodide from ammonia & water purification iodine crystals

Nitrogen Triiodide is a very powerful contact explosive, but like most fun chemicals is not readily available to the general public cheaply. If you want some and have some chemistry skills, watch this video to learn how to make Nitrogen Triiodide at home out of household ammonia and water purification iodine crystals.

### How To: Turn water into ice without a freezer

Here's a fun experiment you can do that will demonstrate the effects that pressure has on the freezing point of a liquid. You will amaze your friends as you do what seems to be impossible, turning water into ice without sticking it in the freezer.

### How To: Minimize the sum of squared error for a regression line in statistics

Learn how to minimize the sum of squared error for regression line problems in stats. Whether you need help studying for that next big stats text or just a hand finishing your homework, you're sure to be well served by this four-part free video math lesson from Salman Khan.

### How To: Heavy Water & Light Ice Experiment

Heavy Water & Light Ice Experiment. What happens? Ice floating over vegetable oil but it decreases in baby oil.

### How To: Graph half an ellipse

If you are given an equation of ellipse in the form of a function whose value is a square root, you may need to simplify it to make it look like the equation of an ellipse. Now equate the function to a variable y and perform squaring on both sides to remove the radical. Now simplify the equation and get it in the form of (x*x)/(a*a) + (y*y)/(b*b) = 1 which is the general form of an ellipse. Now you will have the x and y intercepts which are a and b respectively. Using this values graph the eq...

### How To: Use the Fundamental Rule of Proportions in Algebra

The author in this video explains the concept of fundamental rule of proportions. Fundamental rule of proportions means cross multiply. He explains that to arrive from an equation which has fractions into the one without equation multiply the top of left side with the bottom of right side and equal it with bottom of left side multiplied with top of the right side. In this way proportions can be cross multiplied to arrive at an algebraic expression. If you want to master the rule of proportion...

### How To: Find the area of irregular shapes

This video explains how to find the area of irregular shapes. Draw the shape on a grid or graph paper. This will help you divide your shape into pieces. Draw dotted lines to divide the shape into squares, rectangles or triangles. For instance, if you have an "L" shape, you can divide the shape into two rectangles. Be sure your shapes do not overlap. Calculate the area of each individual shape. The graph paper will help you determine the length and width of each shape. Add the resulting areas ...

### How To: Convert mixed numbers into top heavy fractions

In this video tutorial, viewers learn how to convert mixed numbers to top heavy fractions. This task is very easy, fast and simple. Begin by multiplying the whole number with the denominator and then add the numerator. In the final answer, the numerator will be greater than the denominator. The denominator stays the same and does not change. This video provides several examples and demonstrations for viewers to have a better understanding. This video will benefit those students who are strugg...