Solving Equations: Using An Equation to Solve a Word Problem
This clip explains that, "
what makes equations tricky is that there's no set rule for doing them all. You have to size up each one separately, decide what needs doing, and get it done." The clip then goes through an equation step by step, beginnin...
Ratio and Proportion: Simplifying the Comparing of Fractions by Cross Multiplying
This clip explains that cross multiplying is a shortcut which allows us to determine if two fractions are the same. The fractions are compared by multiplying the numerator of each by the denominator of the other. If the products are the same, then t...
Ratio and Proportion: Problem In Which The Denominator Is Missing, A
This clip explains that, whether it's a numerator or a denominator that's missing, in order to be sure that "
we really have a proportion...the cross products must be equal."
Ratio and Proportion: Practical Problem: French Toast, A
This clip presents a problem involving cooking ingredients needed to make French toast. As in other proportion problems, we are given three pieces of information and have to find the fourth. The problem is solved through the use of cross multiplying...
Ratio and Proportion: Proportions In the Use of Map Scales
This clip presents a problem involving the scale on a road map comparing inches to miles. The clip explains that checking the answer to see that it makes sense is especially important in proportion problems, because "
when the answer is wrong, it's...
Ratio and Proportion: Knowing Whether Two Fractions Are Equal
This clip explains that the way to find out whether two fractions are equal is to write them with a common denominator. If the numerators are equal, the fractions will be equal.
Ratio and Proportion: Solving Word Problems Involving Proportions
This clip presents two word problems involving proportions which require dividing both sides of an equation by the same number. The answers are checked by forming cross products which are equal.
The Meaning of Percentage: Summary: The Meaning of Percentage
This clip summarizes the key points about percentage, stressing at the outset that it's practical to be able to view all fractions with the same denominator. The clip then talks about the different ways we can express the same value in decimal, frac...
Signed Numbers: Introducing Negative Numbers
This clip uses the number line to illustrate that there can be negative numbers as well as positive numbers. Negative numbers on the number line are located to the left of the zero, rather than to the right.
Signed Numbers: Number Line Exercises
This clip offers practice in locating a set of numbers known as "the set of integers" on the number line. The clip explains that the integers include zero, but don't include any fractions, positive or negative.