Activity 2.3 - Zooming into Air (30 min)

Show students Slide 2 of the 2.3 Zooming Into Air PPT. Ask students to discuss what is air made out of, and vote on whether air has mass, and whether air is made of atoms. Note students’ ideas and discuss them as they go through the activity.

View slides 4-8 to zoom into air from large scale down to the smallest droplets so students can see air at the macro and micro scales. While zooming in, discuss how each scale is measured, and if you can see each scale with the naked eye. Use Slides 8-9 to continue to zoom down to the atomic-molecular scale. Ask students if this matched their initial ideas about what air is made out of.

• Note: Slides 4-10 use animations. View in “Presentation Mode” to see the animations.

Show students Slides 11-14, which are about atoms and molecules in air.

• Show students slide 11 and compare percentages of gases in air. Explain to students that even though they are very important, CO₂ and water vapor make up only a very small portion of the molecules in air. Tell students that Argon (Ar) is an inert gas - one of the few elements whose atoms do not bond to other atoms in molecules. Ask students if this matches their ideas about what air is made out of.

Have students make two columns on a piece of paper—a T-chart. Instruct them to label one column “atoms” and the second column “molecules.”

• Display slide 12. Ask students to write the number of each image in the either the “atoms” or “molecules” column. Then have them check their answers with a neighbor.
• Accommodation: Do this activity as a class discussion. Ask students what they think and place the number into the two categories.
• Check for understanding. Ask students if the word “nitrogen” refers to an atom, molecule, or both.
• Ask students: “What is the difference between a nitrogen atom and a nitrogen molecule?”

Use slide 13 to discuss the four key molecules in air: N₂, O₂, H₂O, and CO₂, explaining both structures and formulas. Tell students that the four key atoms that are involved in carbon-transforming processes are: C (carbon), H (hydrogen), O (oxygen), and N (nitrogen). Describe how each of the key molecules in air is made of atoms bonded together.

Accommodation: Use the Molecule 11 x 17 Poster to help students visualize the difference between atoms and molecules.

Show students Slide 14 and tell students that they will need to remember these three facts about atoms in all Carbon TIME units.

• Tell students that nuclear changes include reactions at nuclear power plants and changes that occur in the interior of the sun, but do not happen to common atoms on the Earth’s surface. In Carbon TIME units we treat “weight” and “mass” as equivalent.

Use slides 15-17 to ask students to apply the facts about atoms to air. Ask students to write down their answers to the questions on the back of their T-chart, and then discuss their ideas in groups.

Use Slide 18 to ask students questions to make sure they understand that the facts about atoms apply to all materials, including the materials that people and other living organisms are made of.

• Ask students whether they think that people are made of atoms.
• Ask whether the three facts about atoms apply to the atoms that we are made of. Many students believe that living things in general and people in particular are “special,” not made of just ordinary atoms like non-living materials.
• Ask students if they think that ethanol is made of atoms. Have students recall the lesson where they watched ethanol burn.
• Ask students if the three facts about atoms apply to the atoms that ethanol is made of.
• Ask students if these facts apply to ethanol when it is burned.
• Ask students whether they think that flames contain atoms. (note: flames do contain atoms, as well as forms of energy)
• Ask students if the three facts about atoms apply to the atoms in flames. Use this question to assist students in making the connection between matter and energy.

Show slide 19 of the 2.3 Zooming Into Air PPT.

• Have students take out their Learning Tracking Tool.
• Explain that students will add to the tool after activities to keep track of what they have figured out that will help them to answer the unit driving question.
• Have students write the activity name in the first column, "Zooming Into Air."
• Have a class discussion about what students figured out during the activity that will help them in answering the unit driving question, "what happens when ethanol burns?" When you come to consensus as a class, have students record the answer in the second column of the tool.
• Have a class discussion about what students are wondering now that will help them move towards answering the unit driving question. Have students record the questions in the third column of the tool.
• Example Learning Tracking Tool

Show slide 20 of the 2.3 Zooming Into Air PPT.

• Conclusions: What are three facts about atoms?
• Predictions: Why do we study atoms and molecules even though they are too small to see?
• On a sheet of paper or a sticky note, have students individually answer the exit ticket questions. Depending on time, you may have students answer both questions, assign students to answer a particular question, or let students choose one question to answer. Collect and review the answers.

The conclusions question will provide you with information about what your students are taking away from the activity. Student answers to the conclusions question can be used on the Driving Questions Board (if you are using one). The predictions question allows students to begin thinking about the next activity and allows you to assess their current ideas as you prepare for the next activity. Student answers to the predictions question can be used as a lead in to the next activity.