English Review of Spelling

Overview Although sounds many sound the same in English, they may be spelled differently.  Therefore, many words that sound similar may be spelled very differently, and any English spelling rule is likely to have exceptions. Same Sound, Different Spelling Many similar sounds are expressed by different combinations of letters.  For example, the long a as […]

English Review of Expressing Numbers

Overview Rules for how numbers are expressed in print depend on the formality of the writing task.  When writing is very formal, such as in a book or essay, numbers are spelled out as words.  In less formal writing or in letters, numbers are often expressed as numerals.  When using a specific style, such as […]

Science Review of Dark Matter

Overview The type of energy and matter that we can observe in the universe is thought to be only a small fraction of its total contents, less than 5%.  Dark matter and dark energy have been theorized to make up the rest.  Although scientists cannot observe either dark matter or dark energy directly, evidence for […]

Science Review of Plasma

Overview Plasma is often called the fourth state of matter, as it has properties different from all the other states.  Most of the matter contained in stars, interstellar clouds, and other features of the observable universe is in the plasma state. Definition A plasma is a very hot ionized gas that is made up of […]

Math Review of Fitting Equations to Data

Overview Many real-world situations can be approximated by the relationship between two different variables that fall on a straight line. The linear equation is one model of the data.  Sometimes the task is to predict another value from a small amount of data, while other times it is to find a relationship between large amounts […]

Math Review of Slopes and Intercepts

Overview If the linear equation for a line has been determined, the slope of that line can be found by solving for any two points on the line. Similarly, the slope-intercept equation can be used to find the y-intercept and graph the line.  If any point on a line and the slope are known, the […]

English Review of Word Division

Overview Although it is always better to avoid dividing words, English has rules about dividing words by syllables if necessary.  Words of one syllable cannot be divided.  Words are often divided using prefixes, suffixes, and syllables. Words Not to Divide It is always better to avoid dividing words, because when part of a word is […]