This web site uses JavaScript to dynamically create content. Please ensure your browser supports JavaScript.
Chemicals, the Environment, and You
National Institute of Environmental Health Sciences Home
skip navigation Main Getting Started Teacher's Guide Student Activities About NIH and NIEHS
glossary | map | contact 
Teacher's Guide - return to teacher's guide home hand using a mouse

Lesson 1-Chemicals, Chemicals, Everywhere
Engage

PREPARATION

Activity 1

Arrange for students to have access to computers.

Collect samples of things made of chemicals. Place them on a materials table.

Tip from the field test: To make gathering the materials easier, ask students to bring in one item they think is made of chemicals and one they think is not made of chemicals.

Duplicate and cut out the Item Cards from Master 1.1, Item Cards. Fold them in half to make tent cards. Place the Item Cards on the materials table with the things made of chemicals.

Fold the index cards in half to make tent cards and label them with one of the following titles:

Make a transparency of Master 1.2, Periodic Table of Elements (optional).

Make a transparency of Master 1.3, Elemental Composition of the Human Body.

Activity 2

Arrange for students to have access to computers.

Make 50 mL of a mystery chemical:

Pour the mystery chemical into a 50-mL or larger glass jar and screw the lid on tightly. Place it inside the shoe box. Place the shoe box behind your desk.

Ask students to bring in articles of clothing. Place them and any you have gathered in a basket or box behind your desk.

Activity 3

Arrange for students to have access to computers.

Make a transparency of Master 1.4, Questions for Case Studies.

Duplicate Case Study #1 from Master 1.5, Case Studies of Routes of Exposure, 1 for each student. Decide whether each student or teams will complete Case Studies #2–5 and duplicate the appropriate number.

Procedure

ACTIVITY 1: WHAT IS A CHEMICAL?

1. Place the samples of things made of chemicals and the Item Cards on the materials table.

item cards and items made from chemicals

2. Ask the students to look at the materials table and select one thing that they think is made of chemicals and one thing they think is not made of chemicals. Direct students not to remove the items, but to record the names of the items in their science notebooks.

Tip from the field test: In large classes where it might be difficult for students to see the materials, prepare a list of the names of all the materials and make a copy for each student. Instruct students to circle on the list those materials that are made of chemicals.

You might find that students want more information. They might want to know what you mean by "made of chemicals." They might want you to be more specific about whether they should consider only synthetic items or those that may be toxic. Acknowledge that you have given them limited information, but ask them to do their best to make their choices. Do not provide any assistance at this time.

assessment icon This activity provides you with a good assessment of students' prior knowledge of the concept of chemicals.

3. Once all the students have recorded the items in their notebooks (or circled the items on their lists), ask each student to name one item that is made of chemicals and one that is not. As students tell you their choices, stand by the materials table and separate the items according to student choices into two categories: made of chemicals and not made of chemicals. Continue until all students have shared their ideas. Use two of the tent cards to label the two categories: "made of chemicals" and "not made of chemicals."

place items into two groups: made of chemicals, and not made of chemicals

4. Direct students to look at the groups of substances they think are and aren't made of chemicals. Conduct a discussion by asking questions similar to these:

As you conduct this discussion, rearrange the items on the table several times and use new tent cards to label the new categories: "synthetic" or "naturally occurring"; "toxic" or "nontoxic"; and "bad" or "good."

group items into addtional categories such as toxic/non-toxic and good/bad

National Science Education Standards icon Content Standard B:
…There are more than 100 known elements that combine in a multitude of ways to produce compounds, which account for the living and nonliving substances we encounter.

5. As you progress through the discussion in Step 4, students may realize that they do not know a useful definition for "chemical." Have this definition ready for them:

chemical: any substance that is made of specific elements combined into molecules.

6. As a class, view the segment from the Web site titled Everything Is Made of Chemicals.

Web activity iconTo view the segment, open the Web site in your browser (see instructions for using the Web site). From the main page, click on Web Portion of Student Activities, and then Lesson 1—Chemicals, Chemicals, Everywhere.

Note: If you do not have access to a projection screen for the Web site, set up a computer center where students can view the Web site on their own or in small groups at a later time. At this time, display the transparency of Master 1.2, Periodic Table of Elements, and discuss the following:

water molecule
Water
table sugar molecule
Table Sugar

7. After viewing the Web site or discussing the periodic table, continue by helping students recognize that all of the substances on the materials table are made up of specific molecules, even if the students don't know exactly what they are. Once they recognize this, students will begin to realize that all things are made of chemicals. Ask students to tell you, based on their new understanding, some other things around them that are made of chemicals. Let students continue until you see that they understand that everything around them, or everything in their environment, is made of chemicals.

8. To make sure that the students understand that they, too, are made of chemicals, display a transparency of Master 1.3, Elemental Composition of the Human Body. Let your students know that these elements are combined in many different ways to form thousands of different chemicals that make up the human body.

9. Discuss with students how their original idea about what a chemical is, which led them to their choices in Step 2, is different from the scientific definition of a chemical. Why do they think this is so?

Students will recognize that they hear most about the chemicals that are toxic to humans or the environment. Because of this, students often think of chemicals as only those synthetic substances that are introduced into the environment and cause harm. Help students recognize that they also know a lot about synthetic chemicals that are beneficial to humans, such as pain relievers and other medicines. They also know about naturally occurring chemicals that are toxic to humans, such as hydrogen sulfide (sewer gas) and carbon monoxide, to name two. By the end of the discussion, help students recognize that chemicals can be synthetic or naturally occurring and make up every substance on Earth, even our bodies.

Bridge to Activity 2 by helping students understand that many chemicals, both synthetic and naturally occurring, can be beneficial to humans and the environment. Those chemicals that are not beneficial are the ones we want to know more about so that we can protect ourselves and the environment from harm.

ACTIVITY 2: PROTECT THE TOXICOLOGIST

1. Bring out the shoe box from behind your desk. Tell the students that inside the shoe box is a mystery chemical. Discuss with the students some things they might want to know about the contents of the shoe box before they open it. Ask why it would be important to know these things.

Be sure that students recognize that they would want to know what the chemical is (for example, name; naturally occurring or synthetic; solid, liquid, or gas; how much of the chemical is in the container). Most importantly, they would want to know if it is toxic to the humans in the classroom because they would not want to accidentally expose themselves to a harmful substance.

National Science Education Standards icon Content Standard G:
Students should develop an understanding of science as a human endeavor.

2. Tell the students that they are asking a lot of the same questions that a toxicologist might ask. Write the word toxicologist on the board. Ask students to identify the root of the word, toxic. Underline it on the board. Tell students that toxicologists are scientists who are specially trained to examine the nature of the harmful effects of chemicals on living organisms. They try to understand which chemicals are toxic to living organisms and in what amounts those chemicals are toxic. While they want to know which chemicals might cause death, they are also interested in other toxic effects, such as disease, tissue damage, genetic alterations, and cancer.

3. Select a student (or ask for a volunteer) and tell the student that he or she is a toxicologist. Tell students that you want the student toxicologist to open the shoe box and look at the mystery chemical, but you do not know anything about the chemical. The student toxicologist needs to protect himself or herself in case the chemical is harmful to humans.

Present to the class the large basket or box of clothing. Ask the class to work together to think of items that the toxicologist should wear for protection from exposure to the chemical. Find items in the basket as students suggest them and give the items to the student toxicologist to put on until he or she is dressed in a protective manner that satisfies the class.

assessment icon This activity is engaging and fun for the students, but it also helps you assess students' knowledge of an important concept of toxicology: routes of exposure.

Tip from the field test: You may not have access to a wide variety of true protective gear. Use regular clothing, but ask students what problems there might be with certain items. For example, if students suggest that the toxicologist's hands need to be covered, you could pull out a pair of mittens. Direct the toxicologist to put on the mittens, but ask the class if the mittens are the best choice and why or why not.

As students select an item, question why a toxicologist needs to wear it. Probe for understanding that a toxicologist is concerned about exposure to a chemical by eating or drinking it, by breathing it, and by absorbing it through the skin. Look to see whether the student toxicologist's skin, eyes, mouth, and nose are covered.

4. Once the student toxicologist is dressed protectively, explain that real toxicologists know that chemicals can enter the body in three ways, called routes of exposure: through the mouth by ingestion, through the nose and mouth by inhalation, and through the skin by absorption. Write the list of the three routes of exposure on the board:

Routes of Exposure

checkmark ingestion

checkmark inhalation

checkmark absorption through the skin

Use the list as a checklist and ask students if they think the student toxicologist is adequately protected from all routes of exposure. If not, have them adjust the protective clothing or suggest useful clothing that is not in the basket.

Point out that the mystery chemical could be a solid, a liquid, or a gas. Discuss each form of a chemical and how the form can help determine which routes of exposure are most likely. For example, a gas might be easily inhaled as soon as the container is opened, while a solid might only be harmful if a person touches it or ingests it. In addition, chemicals can change form. For example, dry ice is solid carbon dioxide that quickly becomes a gas. Liquid mercury can evaporate into a gas, causing exposure by inhalation.

Thank the student toxicologist and ask him or her to return the protective clothing to the basket.

Web activity icon5. Tell students that people who work around toxic chemicals protect themselves in ways similar to those the students suggested for the student toxicologist. Provide time for students to view the segment Ride Along with HAZMAT on the Web site.

To find the segment, open the Web site in your browser (see instructions for using the Web site). From the main page, click on Web Portion of Student Activities, then Lesson 1—Chemicals, Chemicals, Everywhere. Select the Ride Along with HAZMAT segment.

men in hazardous material suits
Photo: Corel

6. Tell the students that you will dress protectively and remove the mystery chemical from the container when they are not in the room (because they are not protected). Let them know that they will be able to examine the chemical during the next class if you decide it is safe to do so.

Return to Lesson Plans

 

back   1 | 2 | 3   

next