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Systems and Scale | Lesson 5 - Other Examples of Combustion

Lesson 5: Other Examples of Combustion

Students learn to distinguish organic from inorganic materials and practice explanations of combustion for other organic materials. They also take the unit posttest.

Guiding Question

What is the difference between materials that burn and materials that don’t burn?

Activities in this Lesson

  • Activity 5.1: Molecular Models for Methane Burning (40 min)
  • Activity 5.2: Explaining Methane Burning (20 min)
  • Activity 5.3: Preparing for Future Units: Organic vs. Inorganic (40 min)
  • Activity 5.4: Explaining Other Examples of Combustion (20 min)
  • Activity 5.5: Systems and Scale Unit Posttest (20 min)

Objectives

  • Describe systems and processes in a hierarchy of scales, including atomic-molecular, macroscopic, and large scale.
  • Draw and explain the movements of materials during chemical change (combustion of methane, butane, octane, and candle wax).
  • Classify materials as organic or inorganic based on observable characteristics (organic materials include foods, fuels, and tissues of organisms) or molecular bonds (organic materials have C-C and/or C-H bonds)
  • Explain chemical changes as atoms being rearranged into new molecules (combustion of methane, butane, octane, and candle wax).
  • Identify forms of energy involved in combustion (chemical energy, light, (motion), heat energy) and distinguish them from forms of matter (e.g., fuels) and phenomena (e.g., flames).
  • Explain energy transformations during combustion: Chemical energy stored in C-C and C-H bonds of fuel molecules is transformed into heat and light (combustion of methane, butane, octane, and candle wax).

NGSS Performance Expectations

Middle School

  • Structures and Properties of Matter. MS-PS1-1. Develop models to describe the atomic composition of simple molecules and extended structures.
  • Chemical Reactions. MS-PS1-2. Analyze and interpret data on the properties of substances before and after the substances interact to determine if a chemical reaction has occurred.
  • Chemical Reactions. MS-PS1-5. Develop and use a model to describe how the total number of atoms does not change in a chemical reaction and thus mass is conserved.

High School

  • Chemical Reactions. HS-PS1-4. Develop a model to illustrate that the release or absorption of energy from a chemical reaction system depends upon the changes in total bond energy.
  • Chemical Reactions. HS-PS1-7. Use mathematical representations to support the claim that atoms, and therefore mass, are conserved during a chemical reaction.

Background Information

In this final lesson of the unit, students have completed the inquiry and application sequences for the combustion of ethanol. The activities in the previous lessons were designed to walk students through a cognitive apprenticeship model of Establishing the Problem, Modeling, Coaching, and Fading. The results of the unit posttest will help you determine if your students are ready to move on to the final stage: Fading. After the Fading stage, students will be expected to carry forward concepts from this unit into future units. If the results from your posttest imply that a majority of your students are still struggling with certain concepts, it might be valuable to return to some of the main concepts they are struggling with before moving on to the next Carbon TIME unit.

Activities 5.1 and 5.2 are the Coaching phase of the Application Activity Sequence, which provides students with important less-scaffolded practice with combustion. Students should take more responsibility for their work than in lesson 4, which included the Modeling phase. Students answer the Three Questions for burning methane using the Explanations Tool, coordinating accounts at the macroscopic and atomic-molecular scales. Macroscopic scale accounts (represented here by the Zooming into a Flame) include these components:

  • the structure of the system (the flame in this case) and the movement of materials through the system;
  • the location where chemical change takes place;
  • the materials involved in the chemical change: the reactants going in and the products coming out.

Atomic-molecular scale accounts include three different ways of representing chemical change:

  • molecular models, with twist ties to represent units of energy, that students use to physically rearrange the atoms of the reactants into the atoms of the products;
  • a chemical equation that shows how atoms are rearranged into new molecules in a compact way (but does not account for energy);
  • the Explanations Tool, which provides a way for students to account for changes in matter and energy in writing but answering the Three Questions. 

Activity 5.3 provides students with additional important Foundational Knowledge and Practice (in the Application Activity Sequence) about the fundamental difference between organic and inorganic materials. These two types of material are different in terms of:

  • Origins: All the living organisms on Earth (foods and fossil fuels) have organic materials and originated in living organisms;
  • Chemical energy: Organic materials have more chemical energy;
  • Molecular structure: Organic materials have C-C and C-H bonds.

Activity 5.4 is the Fading phase of the Application Activity Sequence for combustion. It serves as formative assessment for you—you will be able to see how well they understood the ethanol example—and gives students additional practice explaining examples with less support than they had for ethanol and methane.

Activity 5.5 includes summative assessment for the unit. You can track students’ progress by having them take the Unit posttest (identical to the unit pretest) and comparing the results of the two assessments.

Key carbon-transforming processes: combustion

Unit Map

Unit Map for Lesson 5

Talk and Writing

This lesson of the unit represents the fading portion of the Explanations Phase. This means that students are expected to develop explanations for carbon-transforming processes they studied in this unit in new and novel contexts. The table below shows specific talk and writing goals for the Explanations phase of the unit.


Talk and Writing Goals