Write an article based on this "Learn to take great notes Learn to outline Learn how to spell correctly Learn how to concentrate Learn how to do well in school Get subject help."
article: . Still having trouble taking notes that help you later? Try the look, cover, write and check method, aiding your memory to take in the information you are learning. . Outlining can make any assignment easier by breaking it up into easy to understand chunks. Dealing with these pieces rather than trying to wrap your brain around the whole thing may help you excel. . If you want to get perfect points on an assignment you're going to need to be sure it's free of spelling and grammar mistakes. . . Doing well in school is about more than just getting A's. Read about how to succeed in school as a whole. WikiHow offers help in all sorts of subjects, including tutorials in Math, a helping hand in Science, and advice for English. Find more general help in the Education and Communications Category.

Write an article based on this "Purchase a cold pack that contains ammonium nitrate. Put on goggles, a gas mask, and a pair of rubber gloves. Cut open the pack and pour out 80 millilitres (2.8impfloz; 2.7floz) of the ammonium nitrate. Add 70 millilitres (2.5impfloz; 2.4floz) of hot water and stir the mixture. Purify the ammonium nitrate with a coffee filter."
article: Ammonium nitrate, the active ingredient in many cold packs, is essential for making potassium nitrate. Choose a cold pack that has ammonium nitrate as a primary active ingredient. If you don't have enough ammonium nitrate from the first cold pack, purchase a second one as needed. You can find cold packs containing ammonium nitrate from most pharmacy or health stores. You can also buy pure ammonium nitrate online or from laboratory supply stores. Making potassium nitrate involves handling substances that can irritate your eyes, lungs, and skin. To prevent injuries while making this chemical, wear safety goggles, a gas mask, and thick rubber gloves. Use scissors to cut lengthwise along the top of the cold pack. Pour out the contents of the pack into a large measuring bowl marked for millimeters. If you don't have any scissors nearby, you can use a sharp knife instead. Fill a measuring cup with 70 millilitres (2.5impfloz; 2.4floz) of hot waterhot enough to notice the temperature but not boiling or near-boiling. Pour the hot water into the ammonium nitrate and stir thoroughly with the water. Pour slowly to prevent the solution from splashing up and causing accidental skin irritation. Continue stirring until the ammonium nitrate dissolves completely into the hot water. Some cold packs use ammonium nitrate and a mixture of other chemicals that can dilute your final product. To prevent this, place a coffee filter over a separate measuring bowl and pour the ammonium nitrate solution slowly over the empty bowl. When you've finished pouring, discard the coffee filter immediately to prevent it from contaminating the purified solution.

Write an article based on this "Calculate the actual distance you'd have to traverse to get to the horizon by using the following formula. Increase R by 20% to compensate for the distorting refraction of light rays and to arrive at a more accurate measurement. Understand how this calculation works."
article:
d = R * arccos(R/(R + h)), where d = distance to horizon R = radius of the Earth h = height of eye The geometric horizon calculated using the method in this article may not be the same as the optical horizon, which is what your eye actually sees. Why is this? The atmosphere bends (refracts) light that is traveling horizontally. What this usually means is that a ray of light is able to slightly follow the curvature of the earth, so that the optical horizon is a bit further away than the geometric horizon. Unfortunately the refraction due to the atmosphere is neither constant nor predictable, as it depends on the change of temperature with height. There is therefore no simple way to add a correction to the formula for the geometric horizon, though one may achieve an "average" correction by assuming a radius for the earth that is a bit greater than the true radius. This will calculate the length of the curved line that follows from your feet to the true horizon (shown in green in this image). Now, the arccos(R/(R+h)) portion refers to the angle that is made at the center of the Earth by the line going from the true horizon to the center and the line going from you to the center. With this angle, we multiply it by R to get the "arc length," which, in this case, is the distance that you are looking for.