Three-dimensional Learning Progression Lesson 2 focuses on essential foundational knowledge that students will need to achieve the objectives for this unit. Although most students will be familiar with the words “atoms” and “molecules,” they may not be able to use ideas about atoms and molecules to explain events in the world. This lesson introduces the hierarchy of scales and key facts about atoms that students will use in all future units. The activities in this lesson serve as the Foundational Phase of the Instructional Model, where students are introduced to key ideas and practices that they will use throughout the rest of the Systems and Scale unit. Key Ideas and Practices for Each Activity In Activity 2.1, the Powers of Ten video introduces a fundamental scientific principle: Our world is organized into a hierarchy of systems at different scales, most of which are too small or too large for us to see directly. Powers of Ten is one way to step down or step up through the different scales so that students can make accurate comparisons between sizes, and make connections between processes happening on one scale with processes happening on another. Carbon TIME focuses on the connections among systems and processes at four different scales: The large scale: ecosystems and Earth systems (roughly from about 1 km (103 m) to the size of the Earth: over 10,000 km (107 m)) The macroscopic scale: systems and processes we can see with our naked eyes (roughly from about 1 mm (10-3 m) to one kilometer (103 m)). The cellular scale: systems and processes that happen inside cells, some of which we can observe with a microscope (roughly from about 10-4 m to 10-7 m) The atomic-molecular scale: Atoms and molecules (roughly from about 10-10 m to 10-8 m). Note that between the atomic-molecular and the macroscopic scale there is another broad benchmark scale—the microscopic or cellular scale. While Carbon TIME does not emphasize the microscopic scale, students still need to understand that atoms and molecules are much smaller than this benchmark scale; even the best light microscopes cannot see atoms or molecules. In Activity 2.2, an introductory and optional activity at the high school level, students sort a set of cards with images of systems into the four benchmark scales and talk about how a particular system at the macroscopic scale is part of a larger system, and also composed of smaller systems, including atoms and molecules. This activity will help students understand that processes and systems occur simultaneously on each scale. In Activity 2.3, students discuss air at all four benchmark scales. Air is an especially important material that Level 2 students may not recognize as a material that has mass. Many Level 2 students think of air as ephemeral, weightless, and not necessarily composed of atoms or molecules. The 2.3 Zooming Into Air PPT and discussion in this activity will help students understand how air looks at multiple scales, from large scale down to atomic-molecular scale. Students will also learn that air contains four important molecules: N2, O2, H2O, and CO2, and the atoms that these molecules are made of are C, H, O, and N. These atoms are the key atoms in all carbon-transforming processes. Importantly, the student is introduced to three essential facts about atoms that they will be expected to remember and use throughout all Carbon TIME units: Atoms last forever (except in nuclear changes). Atoms make up the mass of all materials. Atoms are bonded to other atoms in molecules. In Activity 2.4, the 2.4 Atoms and Molecules Quiz checks students understanding about the hierarchy of scales and the three key facts about atoms and molecules. The quiz requires students to apply these ideas to new situations that they have not yet discussed in class. In Activity 2.5, students practice using two essential tools in Carbon TIME units: Digital balances are used in the units to detect movement of atoms (the Movement Question) by measuring differences in mass. This activity introduces students to the balances, allows every student to weigh something, and compares results. Bromothymol blue (BTB) is an indicator that changes from blue to yellow in response to high levels of CO2. Students will see how blue BTB responds to a gas that most students know as a source of CO2: their exhaled breath. Key carbon-transforming processes: Combustion Content Boundaries and Extensions [This could be a place to note deliberately omitted details and simplifications, referring to the content simplifications document if necessary, as well as suggested extensions or additional readings (with more details in the Activity pages).]
