Ch 2 section 3 review study helper Scientific Illustrations Photographs and drawings model and illustrate ideas and sometimes make new information clearer

Ch 2 section 3 reviewstudy helper

Scientific Illustrations

• Photographs and drawings model and illustrate ideas and sometimes make new information clearer than written text can.

• For example, a drawing of an airplane engine shows how all the parts fit together much better than several pages of text could describe it.

Drawings, Tables, and GraphsDrawings, Tables, and Graphs

33

Drawings• A drawing is sometimes the best choice to

show details.

• A drawing can emphasize only the things that are necessary to show.


33

• A drawing also can show things you can’t see. • For example, you could draw the outline of

two continents to show how they might have fit together at one time.

Drawings

• Drawings can show hidden things, as well. For example, a drawing can show the details of the water cycle.


33

Drawings


33

Photographs

• A still photograph shows an object exactly as it is at a single moment in time.


33

• Movies show how an object moves and can be slowed down or sped up to show interesting features.

Tables and Graphs

• A table displays information in rows and columns so that it is easier to read and understand.


33

Tables and Graphs• A graph is used to collect, organize, and

summarize data in a visual way.


33

• Three common types of graphs are line, bar, and circle graphs.

• A line graph shows the relationship between two variables.

• A variable is something that can change, or vary, such as the temperature of a liquid or the number of people in a race.

• Both variables in a line graph must be numbers.

Tables and Graphs• One variable is shown on the horizontal axis,

or x-axis, of the graph.


33

• The other variable is placed along the vertical axis, or y-axis.

• A line on the graph shows the relationship between the two variables.

Bar Graph

• A bar graph uses rectangular blocks, or bars, of varying sizes to show the relationships among variables.


33

Bar Graph


33

• One variable is divided into parts.• The second variable must be a number. • The bars show the size of the second variable.

Circle Graph• A circle graph shows the parts of a whole.


33

• Circle graphs are sometimes called pie graphs.

• Each piece of pie visually represents a fraction of the total.

Circle Graph• A circle has a total of 360°. To make a circle

graph, you need to determine what fraction of 360 each part should be.


33

Circle Graph


33

• First, determine the total of the parts.

• The total of the parts, or endangered species, is 367.

• One fraction of the total, Mammals, is 63 of 367 species.

• Set up a ratio and solve for x:

Reading Graphs• When you are using or making graphs to

display data, be careful—the scale of a graph can be misleading.


33

• A broken scale can be used to highlight small but significant changes, just as an inset on a map draws attention to a small area of a larger map.

• Always analyze the measurements and graphs that you come across. If there is a surprising result, look closer at the scale.

Reading Graphs• This graph does not start at zero, which

makes it appear that the number of species has more that quadrupled from 1996-2002.


33

Reading Graphs• The actual increase is about 20 percent, as

you can see from this full graph. The broken scale must be noted in order to interpret the results correctly.


33

Section CheckSection Check

33

Suppose you have two variables, for example, how much salt you eat in a day and how much water you drink, and you want to visually depict their relationship across time. What visual tool might you use to show this relationship?

Question 1


33Answer

A line graph shows the relationship between two variables. Line graphs are excellent waysto quickly see the relationship between a variable plotted on the X axis and one plotted on the Y axis.


33

When you put numerical data into rows and columns, you are creating a _______.

Question 2

A. calculationB. graphC. tableD. waveform


33Answer

The answer is C. Rows and columns of numbers make up a table.


33

Suppose you want to visually demonstrate how much of a given area is woodland, how much is grassy but has no trees, and how much has been developed. With different segments like this to consider, how might you choose to show the relationship of parts to the whole?

Question 3


33Answer

Use a circle chart. A circle chart, or “pie chart,” is ideal for visually demonstrating how the different segments go together to form the whole.

Documents

Ch 2 section 3 review study helper Scientific Illustrations Photographs and drawings model and illustrate ideas and sometimes make new information clearer