Ratios can be written in a wide variety of different way: as fractions, as decimals, and as percents.,with a colon, with a slash, as a fraction and even as a baseball batting average. Here we compare a decimal ratio and a percent by building decimal and percent tables in the same way and compare their patterns to the ratio patterns we are used to. Ask students what other ways of expressing ratios are there.
Category: Ratio
Ratio and Proportion
We think about ratio tables in terms of motion. Move up 2 and over 1, or move up 1 and over 2. In this way we build proportional patterns. By coloring the cells we land on like knights in a chess table, we can see the proportions of different ratios. These proportions build linear patterns on the ratio table and introduce us to the very important concept of slope
Division and Ratio
We can make a division table just like we made a multiplication table. Division is surprisingly our most important operation in terms of most of the problems we solve in our daily lives. Division produces numbers we call fractions or rationals and functions we call ratios. With spreadsheets we concentrate on ratios and on the patterns of ratios.
Magic Rectangle
Multiplication tables have some wonderful and quite surprising patterns. This is one of them. Draw any rectangle in a multiplication table and you will find that the products of opposite corners are equal. For example a rectangle around a full 12 by 12 table will be 1144 and 1212. Try it, is it always true? Why?
Shapes
Shapes introduces student to changing the colors in cells and to changing the shapes of cells by dragging the column or row separators in the address axes. Students can use spreadsheets as drawing tools and can create some wonderful pictures with them. Spreadsheets can thus be tools for visualizing mathematics as well as adding the arts to technology and math.