Activity 5.3 - Preparing for Future Units – Organic vs. Inorganic (40 min)

Ask students to discuss why ethanol burns like wood, even though it looks like water. Open 1.2 Expressing Ideas and Questions Tool for Ethanol Burning from the first activity. Show slide 4, where students recorded ideas about the difference between ethanol and water.

• Ask the students if they have any new ideas to add to the list now that the unit is over, or if there are any ideas there that should be removed or edited.
• Have students summarize some of their initial ideas about this question. Check to see whether some students are moving beyond labeling materials as “flammable” to thinking about chemical properties of flammable materials.
• Check whether the students mention chemical energy or C-C and C-H bonds.

Use the following slides in 5.3 Organic vs. Inorganic PPT to zoom into water, ethanol, and wood to examine how they differ at an atomic-molecular scale.

• Show students slides 4-8 to zoom in to water, ethanol, and wood from the macroscopic down to the atomic-molecular scale. Tell students that the materials are similar in the kinds of atoms that they are made of, but that they are different in the kinds of bonds between the atoms: ethanol and wood have high-energy C-C and C-H bonds; water does not. Tell students that wood is a mixture of many substances, and that cellulose is the most abundant of these substances.
• Show students the Slides 8 and 10 to point out that the atoms found in the three materials are similar.
• Show students Slides 11-13 to point out that the bonds between the atoms are different: ethanol and wood have high-energy C-C and C-H bonds, and that water does not.

Contrast materials that are organic vs. inorganic.

• Show students Slides 14-17 to contrast materials that burn (fuels) with materials that do not burn. Explain to students that the difference between the two groups of materials is in the bonds, not the atoms.
• Show students Slide 18 to introduce and label these two types of materials. Tell students that in this context, organic is a chemical term - it does not mean “natural” or refer to a certain kind of food that is grown without pesticides.
• Show students Slide 19 to point out that food and the bodies of humans and other animals are made largely of water and organic materials: carbohydrates, fats, and proteins. Tell students that they will return to the chemical composition of these organic materials in later Carbon TIME units.

Show slide 20. Tell students that scientists define “organic” and “inorganic” in terms of chemical composition. Explain to students that even if we do not know the chemical composition of a material, we can judge whether it is organic or not based on where it comes from. Tell students that organic materials include:

• foods or materials made from foods;
• fuels or materials made from fuels;
• bodies of living things or materials made from the bodies of living things.

Divide students into pairs. Give each pair a copy of 5.3 Materials Cards. Tell students to use the 5.3 Organic vs. Inorganic Worksheet to sort the cards into organic and inorganic groups using two different criteria: 1) the origins of the materials: foods, fuels, and the bodies of living things versus other materials, and 2) the chemical structures of the materials: materials with C-C and C-H bonds versus materials without those bonds.

Show slides 21 and 22. Ask students to share what materials they sorted into each group using the notes on their worksheet.

• Look for outliers and discuss any discrepancies. Discuss the sorting until the class reaches a consensus about which materials belong in which group.
• If consensus is difficult to reach, consider pausing to reviewing the criteria for distinguishing between organic vs. inorganic materials in the ppt.
• Discuss the last question on the worksheet with students about how to decide whether an unknown liquid if flammable. Note whether the students suggest using the criteria above—origins and chemical composition—as ways to decide.

If your students are advanced and you would like to discuss chemical bonding with them in terms of the energy of valence electrons, you can use the 5.3 More About Chemical Energy Reading as a basis for this discussion. This level of detail is NOT necessary for students to be successful in any of the Carbon TIME units.

Show slide 23 of the 5.3 Organic vs. Inorganic PPT.

• Have students take out their Learning Tracking Tool for Systems and Scale.
• Have students write the activity name, "Organic vs. Inorganic" and their role “Explainer” in the first column.
• Have a class discussion about what students did during the activity. 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 figured out during the activity that will help them in answering the unit driving question. When you come to consensus as a class, have students record the answer in the third 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 fourth column of the tool.
• Have students keep their Learning Tracking Tool for Systems & Scale for future activities.
• Example Learning Tracking Tool

Show slide 24 of the 5.3 Organic vs. Inorganic PPT.

• Conclusions: What does it mean when someone says that a molecule is organic in science?
• Predictions: Why do you think ethanol burns and water does not?
• 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.