Science Journal  One way to record information, and express how you think about a topic in science is by writing in your Science Journal. It also lets you show how much you know about a subject. There are many different kinds of Science Journal assignments. You may be asked to pretend you are a scientist, a TV reporter, or a committee member of a local environmental group and write from that point of view. Maybe you will be communicating your opinions to a member of Congress, a doctor, or to the editor of your local newspaper. Sometimes, you will summarize information, make an outline or a diagram, or write a letter or a paragraph in your Science Journal.

Classifying
You may not realize it, but you make things orderly in the world around you. If you hang all your shirts together in the closet or if your favorite CDs are stacked together by performer, you have used the skill of classifying. Classifying is the process of sorting objects or events into groups based on things they have in common. When classifying, first look closely at the objects or events to be classified. Then, select one characteristic or feature that is shared by some members in the group but not by all.

Place those members that share that feature into their own group. You can classify members into smaller and smaller groups based on similar characteristics.

What do you do with the dishes after they are washed? You classify them as you put them away, as shown in Figure 2. You separate the silverware from the plates and glasses. Forks, spoons, and knives each have their own place in the drawer. You would keep separating the dishes until all are classified and put away. Remember that all the smaller groups still share the common feature of being an eating utensil.

Sequencing
A sequence is an arrangement of things or events in a certain order. When you are asked to sequence objects or events, decide what comes first, then think about what should come next. Continue to choose objects or events until all are in order. Then, go back over the sequence to make sure each thing or event in your sequence logically leads to the next.

A sequence you are familiar with is alphabetical order. Another example of sequence would be the steps in a recipe, as shown in Figure 3. Think about following a recipe. Steps in a recipe for chocolate-chip cookies have to be followed in order for the cookies to turn out right.

Concept Mapping
If you were taking a trip in a car, you would probably take along a road map. The road map shows you where you are, where you are going, and other places along the way.

A concept map is similar to a road map. But a concept map shows relationships among ideas (or concepts) rather than places. A concept map is a diagram that shows how concepts are related visually. Because the concept map shows relationships among ideas, it can make the meanings of ideas and terms clear and help you understand better what you are studying.

Three types of concept maps are described here: a network tree, an events chain, and a spider map.

Network Tree  Look at the concept map about U.S. currency in Figure 4. This is called a network tree. Notice how some words are in rectangles while others are written across connecting lines. The words inside the rectangles are main ideas. The lines in the map show connections between ideas. The words written on the lines describe relationships between concepts.

When you construct a network tree, write down the topic and list the major concepts related to that topic. Look at your list and begin to put the ideas or concepts in order from general to specific. Branch the related concepts from the major concept and describe the relationships on the lines.

Events Chain  An events chain map is used to describe concepts in order. In science, an events chain can be used to describe a sequence of events, the steps in a procedure, or the stages of a process.

When making an events chain, first find the one event that starts the chain. This event is called the initiating event. Then, find the next event in the chain and continue until you reach an outcome. Suppose you are asked to describe what happens when your alarm clock rings. An events chain map describing the steps might look like Figure 5.

Cycle Map  A cycle concept map is a special type of events chain map.

In a cycle concept map, the series of events does not produce a final outcome. The last event in the chain relates back to the initiating event. Because there is no outcome and the last event relates back to the initiating event, the cycle repeats itself. Look at the cycle map describing the relationship between day and night in Figure 6.

Spider Map  A fourth type of concept map is the spider map. This is a map that you can use for brainstorming. Once you brainstorm ideas from a central idea, you may find you have a jumble of ideas. Many of these ideas are related to the central idea but are not necessarily clearly related to each other. As illustrated by the spider map in Figure 7, you may begin to separate and group unrelated terms so that they become more useful by writing them outside the main concept.

Making and Using Tables  Browse through your textbook and you will notice tables in the text and in the activities. In a table, data or information is arranged in a way that makes it easier for you to understand. Activity tables help organize and interpret the data you collect during an activity. Most tables have a title. The title tells you what the table is about. A table is divided into columns and rows. The first column lists items to be compared. In Figure 8, a collection of recyclable materials is being compared in a table. The row across the top lists the specific characteristics being compared. Collected data are recorded within the grid of the table. To make a table, list the items to be compared down in columns and the characteristics to be compared across in rows.

The title of the table in Figure 8 is "Recycled Materials." What is being compared? This table shows the different materials being recycled and on which days they are recycled. To find out how much plastic, in kilograms, is being recycled on Wednesday, locate the column labeled "Plastic (kg)" and the row "Wed." The datum in the box where the column and row intersect gives the answer. Did you answer "0.5"? How much aluminum, in kilograms, is being recycled on Friday? If you answered "1.0," you understand how to use the parts of the table.

Making and Using Graphs
After scientists organize data in tables, they often show the data in a graph. A graph is a diagram that shows the relationship of one item or variable to another. A graph makes interpretation and analysis of data easier. There are three basic types of graphs used in science: the line graph, the bar graph, and the circle graph.

Line Graphs  A line graph is used to show the relationship between two variables. The variables being compared go on two axes of the graph. The independent variable always goes on the horizontal axis, called the x-axis. The independent variable is the condition that is being changed. The dependent variable always goes on the vertical axis, called the y-axis. The dependent variable is any change that results from the changes in the independent variable.

Suppose your class started to record the amount of materials they collected in one week for their school to recycle. The collected information is shown in Figure 9.

You could make a graph of the materials collected over the three days of the school week. The three weekdays are the independent variables and are placed on the x-axis of your graph. The amount of materials collected is the dependent variable and would go on the y-axis. After drawing your axes, label each with a scale. The x-axis lists the three weekdays. To make a scale of the amount of materials collected on the y-axis, look at the data values. Because the lowest amount collected was 1.0 and the highest was 5.0, you will have to start numbering at least at 1.0 and go through 5.0.

Next, plot the data points for collected paper. The first pair of data you want to plot is Monday and 5.0 kg of paper. Locate "Monday" on the x-axis and locate "5.0" on the y-axis. Where an imaginary vertical line from the x-axis and an imaginary horizontal line from the y-axis would meet, place the first data point. Place the other data points the same way. After all the points are plotted, connect them with the best smooth curve. Repeat this procedure for the data points for aluminum. Use continuous and dashed lines to distinguish the two line graphs. The resulting graph should look like Figure 10.

Bar Graphs  Bar graphs are similar to line graphs. They compare data that do not continuously change. In a bar graph, vertical bars show the relationships among data.

To make a bar graph, set up the x-axis and y-axis as you did for the line graph. The data are plotted by drawing vertical bars from the x-axis up to a point where the y-axis would meet the bar if it were extended. Look at the bar graph in Figure 11 comparing the mass of aluminum collected over three weekdays. The x-axis is the days on which the aluminum was collected. The y-axis is the mass of aluminum collected, in kilograms.

Circle Graphs  A circle graph or pie graph uses a circle divided into sections to show data. Each section represents part of the whole. All the sections together equal 100 percent.

Suppose you wanted to make a circle graph to show the number of seeds that sprouted or grew from a package of seeds. You count the total number of seeds. You find that there are 143 seeds in the package. This represents 100 percent, the whole circle. You plant the seeds, and 129 seeds sprout. The seeds that sprouted will make up one section of the circle graph, and the seeds that did not sprout will make up the remaining section.

To find out how much of the circle each section should take, divide the number of seeds in each section by the total number of seeds. Then multiply your answer by 360, the number of degrees in a circle. Round to the nearest whole number. The section of the circle graph in degrees that represents the seeds sprouted is shown in Figure 12 below.

To plot these data on a circle graph, you need a compass and a protractor. Use the compass to draw a circle. It will be easier to measure the part of the circle representing the seeds that did not sprout, so subtract 325° from 360° to get 35°. Draw a straight line from the center of the circle to the edge of the circle. Place your protractor on this line and use it to mark a point at 35°.

Use this point to draw a straight line from the center of the circle to the edge. This is the section for the group of seeds that did not grow. The other section represents the group of 129 seeds that did grow. Label the sections and title your graph.