# Hot Education Posts

### How To: Make potassium nitrate at home

Believe it or not, there are cheap ways to make potassium nitrate for your chemistry experiments. And the key ingredient… "sodium-free" salt.

### How To: Find the Percent Given Two Numbers

Whether you're shopping for deals, need help with a little math, or any number of other occasions, it's a valuable skill to know how to quickly figure out a percentage given two numbers.

### How To: Find the area & perimeter of triangles & squares

When you are figuring the area of a square, you only need to know the height and width of the shape. Once you know the height and width, multiply them to get the area of the square. To find the perimeter of the square, add all four sides together. To find the area of a triangle, multiply together two of the sides (not the hypotenuse) and then multiply that figure by 1/2. To find the perimeter of the triangle, add all three sides together.

### How To: Make Potassium Chlorate from Ordinary Household Bleach and Salt Substitute

If you're not just a chemistry nerd, but also a firearms freak and explosives nut, then this home brew chemistry concoction is just what you need for some cheap homemade potassium chlorate. It's a mixture of potassium, chlorine and oxygen (KClO3) and is used for such things as gun primers, propellents, and explosives (when mixed with the appropriate fuel). And guess what? NurdRage is going to show you the steps for this makeshift potassium chlorate.

### 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: 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: Find the formula of a piecewise function given a graph

This video shows how to find the formula of a piecewise function when given a graph. The first step is to write a definition for the graph, which is done by identifying the different domains shown in the graph. The second step is writing formulas for each domain specified by the lines in the graph. The point-slope formula is used to identify the slope and y-intercept for the leftmost domain, which has a sloped line. A point and horizontal line make for simpler equations in the other pieces of...

### 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: 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 Be Your Own SpaceX: Design, Build & Test Liquid-Fueled Rocket Engines

Move over NASA— SpaceX is taking over. Well, not really. But today, the privately funded spacecraft company broke all expectations when their Dragon capsule fell to a soft landing in the Pacific Ocean, completing an undoubtedly successful demo flight of nearly two full trips around Earth. It was the first re-entry of a commercial spacecraft ever, bringing commercial space transportation closer to reality.

### How To: Find the formula of a given sequence

In this tutorial, we learn how to find the formula of a given sequence. First, you need to decide what you're starting with. Start with a1, then continue on with a2, a3, and a4. Eventually, you will have an "An". You will have an "n" in your numerator and the denominator will start between the numbers of your fractions. Look to see if that works, then you have to see where the signs alternate on the fractions. Write in any negatives that you have, then figure your power out. Once you follow t...

### How To: Do normal probability calculations on a calculator

Probability computation is a complex process and even using a calculator can be difficult. But normal probability calculations can be performed quickly with the help of calculator once you know how to use it. So when you have to calculate a probability from a normal distribution you can use the functions on your scientific calculator. You can use the normal CDF function from you calculator to compute the area under a normal curve. The function requires lower band and upper band values, the me...

### Classic Chemistry: Colorize Colorless Liquids with "Black" Magic, AKA the Iodine Clock Reaction

Want to make boring old colorless water brighten up on command? Well, you can control the color of water with this little magic trick. Actually, it's not really magic, but a classic science experiment known commonly as the iodine clock reaction, which uses the reactions between water and chemicals to instantly colorize water, seemingly by command. You can use different colorless chemicals to produce different colors, and you can even make the color vanish to make the water clear again.

### How To: Prove a triangle inscribed in a circle is right angled

When a triangle is inserted in a circle in such a way that one of the side of the triangle is diameter of the circle then the triangle is right triangle. To prove this first draw the figure of a circle. Now draw a diameter to it. It can be any line passing through the center of the circle and touching the sides of it. Now making this as the side of a triangle draw two lines from the ends of the diameter to a point on the circle. Now join the center of the circle to the other vertex of the cir...

### How To: Make oxygen from permanganate and hydrogen peroxide

C For Chemistry delves into the chemistry of science experiments. This chemist knows what he's talking about. These chemistry experiments are not only fun, but very educational for all of those interested in scientific chemical reactions and properties.

### How To: Find the equation of a line given 1 point

Need help figuring out how to find the equation of a line given a single point? Learn how with this free video 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: Simplify a quadratic formula result

In this video the tutor shows how to simplify a quadratic formula result. You can solve a quadratic equation using the quadratic formula. The first thing you have to do when given the quadratic equation is bring all the terms to one side so that you have a zero on the other side of the equals to sign. Now the formula to calculate the roots of the quadratic equation ax*x + bx + c = 0 is x = (-b + root of(b*b - 4*a*c) ) / 2 * a. The other root can be obtained by using the minus sign before the ...

### How To: Find the perimeter & area of a complex figure

In this video tutorial the author shows how to find the perimeter and area of a complex figure. He shows that a complex figure can be subdivided into standard geometric figures. In the current example he divides the complex figure into a rectangle and a triangle. Now he computes the perimeter by adding the three sides of the rectangle and the two sides of the triangle. Similarly he computes the individual areas of the rectangle and the triangle and finally adds then up to find the area of the...

### How To: Use the ratio formula to find coordinates of a point

This video is recorded in a mathematics class room. It is very clear by the sound and picture. The faculty here is explaining that the ratio between two numbers can be found using various formulae and methods. For example, 3:1 is the ratio between p and q. Likewise he explained the other formulae and methods.

### How To: Subtract fractions with borrowing

This how-to video describes how to subtract fractions using the borrowing method. The video shows viewers everything they need to know including basic subtraction of fractions, how to find common denominators, to the more difficult borrowing techniques. The narrator in this video does a great job of keeping things simple enough for anybody to understand. At the same time, he goes in depth enough that you really get how to use this technique. The voice in this video is very calm and clear. Thi...

### How To: Solve a line integral over a closed path

Line integrals will no longer be the feared terrorist of the math world thanks to this helpful guide from the Khan Academy. Marvel at the ease in which the integral is taken over a closed path and solved definitively. Then take out a sheet of paper and see if you can do the same.

### How To: The Trick to Stabbing a Balloon Without Popping It

A balloon's worst fear is a sharp object, so usually when you puncture a balloon, it pops in your face. Not with this science trick! To puncture a fully blown up latex balloon without popping it, you'll need a pointed metal or wooden skewer and some plain old dish soap. That's it.

### How To: How Do You Balance 14 Nails on a Single Nailhead? Find Out with This DIY Gravity Puzzle

This little brain game is all about engineering a lower center of gravity. The idea has been around forever, but most people still don't know how to do it. Trying to stack nails above the balance point will raise the CG and make the structure unstable. Here's how you can lower the CG to make a very stable structure and impress your friends.

### How To: Understand and Provide Indirect Care for CNA Certification

What is Indirect Care? Does it affect the CNA's exam result? Indirect Care entails your behavior in terms of how you communicate with the resident, valuing residents' rights and residents' safety and security. Indirect Care is absolutely important because: (1) it is a graded performance, (2) it has separate score ratings, and (3 )it greatly affects the testees' overall performance during the clinical skills exam.

### How To: Do a gravity experiment with a lemon and penny

Do you think it's easy to place a coin on top of a lemon that is floating in a glass of water? If you said yes, you're probably right.

### How To: Find the area of an oblique triangle using formulas

In this tutorial the instructor shows how to find the area of an oblique triangle using different formulas. To find the area of an oblique triangle there are different formulae. The first formula to calculate the area of a triangle is area A = (1/2) * a * b * Sin(C), where a and b are the lengths of the two sides of the triangle and C is the value of the angle of the triangle that lies in between the two sides a, b. Now substitute these values in the given formula to find the area if you have...

### How To: Find Leg Lengths and Hypotenuse of a 45 45 90 Triangle

A 45 45 90 triangle is a special right triangle because you can use short cuts to find leg length and hypotenuse length. This video solves two problems involving leg length and hypotenuse length.

### How To: Make Water Freeze into Ice Instantaneously

Have you ever seen water freeze instantly? This "Quick Clip" shows some of my personal experiences with making instant ice using a bottle of water supercooled in a freezer.

### 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 a circle when you know the diameter

In this video, it is shown how to calculate the area of a circle where the diameter is given. The formula for calculating the area of a circle is pi multiplied by square of radius. Radius is actually half of the diameter. In this video, the diameter is given as 10.6 meters. Hence, the radius will be half of 10.6 which is equal to 5.3 meters. Now, to find the area we shall multiply pi with the square of 5.3. Square of 5.3 is 28.09. If we multiply 28.09 with pi we shall get the area of the circ...

### How To: Make Glow Powder Out of Household Chemicals

Glowing substances have always held a powerful appeal to people, and making new ones can be a lucrative business. If you need some glow powder for a project of yours, watch this video to learn how to make DIY glow-in-the-dark powder out of normal household chemicals.

### How To: Weather Forecast And Weather Predict Without Technology

We have no control on the weather yet it is a part of our lives which influence what we do, what we eat, what we wear and many times where we live. How did people predict the weather before there was the Internet, television, radio or the weatherperson with all of their gadgets?

### How To: Make a simple dry ice bomb

When I was a kid, the 4th of July was my favorite holiday for one simple reason...the joy of making things go BOOM! Somewhere along the line that fun was taken away by politicians. It's time to put the fun back in celebrating freedom. From your friends at America's favorite podcast, Anarchy-X.

### How To: Plot a real number on a number line

This video tells you how to plot a real number on a number line. For example consider -3.1. You know -3.1 lies between -3 and -4. You also know -3.1 lies very close or next to 3. So all you have to do is, put a point just before -3. Now you have marked -3.1 on a number line. Similarly you can point any real number on a number line. It is quite an easy job to plot real numbers on a number line.

### News: Light dry ice on fire

Impossible, right? Ahh, well science says fire and ice can and do coexist.

### How To: Find the Slope Given 2 Ordered Pairs

Slope is the change in Y over the change in X. Written out, the formula looks is as follows: (y2-y1)

### How To: Make fireballs you can hold in your hand

This flame you CAN hold, without burning your skin off. Learn to make fireballs you can hold in your hand. This amazing video tutorial shows you how to do it. All you'll need for this little science experiment or fiery weapon is 100% cotton cloth, scissors, lighter fuel, cotton string, and a needle. Be careful to follow the directions in this how-to video carefully otherwise you'll really be playing with fire.

### How To: Turn multiplication into sum

This is a handy math trick that show you how to turn a multiplication problem into a sum problem. An unusual way to perform a multiplication. You only need to be able to sum, halve and double numbers. It is not efficient, but it is rather intriguing and fun.

### How To: Dissolve gold in aqua regia to make tetrachloroauric(III) acid (gold chloride)

Aqua regia (königswasser in German) is a very corrosive liquid made from a mixture of nitric acid and hydrochloric acid (1:2 - 1:3). This chemical mixture is so corrosive that it can even dissolve gold, and that's what you'll learn about in this video.

### How To: Do long division with remainders

This video goes through the step by step process of doing long division with remainders. Multiple examples are used throughout the video to give the viewer a better idea of how to properly complete the difficult task. Perfect for anyone learning long division for the first time, or for anyone attempting to relearn long division after forgetting how to do the process (an all to common occurrence in a world with calculators on every cell phone).