Here, we present two ways to think about how lessons are sequenced in the Ecosystems Unit. The Instructional Model, immediately below, emphasizes how students take on roles of questioner, investigator, and explainer to learn and apply scientific models they can use to answer the driving question. Further below, the Unit Storyline Chart highlights the central question, activity, and answer that students engage with in each lesson of the Ecosystems Unit. Instructional Model Like all Carbon TIME units, this unit follows an Instructional Model (IM) designed to support teaching that helps students achieve mastery at answering the driving question through use of disciplinary content, science practices, and crosscutting concepts. To learn more about this design, see the Carbon TIME Instructional Model. During the inquiry portion of the unit (Lesson 2), the students move from making observations of a simulated meadow ecosystem to identifying patterns, eventually using these patterns to make evidence-based arguments. During the explanation portion of the unit (Lessons 3, 4, and 5), students makes connections across scales (from atomic-molecular scale to ecosystem scale) to explain patterns and changes in ecosystems. Across the unit, classroom discourse is a necessary part of three-dimensional Carbon TIME learning. The Carbon TIME Discourse Routine document provides guidance for scaffolding this discourse in lessons. The core of the Carbon TIME IM is the Observation, Patterns, Models (OPM) triangle, which summarizes key aspects to be attended to as the class engages in unit inquiry and explanation. The OPM triangle for the Ecosystems Unit, shown below, articulates the key observations students make during the unit investigation, the key patterns they identify through analyzing their investigation data, and the central scientific model that can be used to answer the unit’s driving question. Observations, Patterns, Models, and Explanations in the Ecosystems Unit Unit Storyline Chart Another way to familiarize yourself with the sequence of lessons in the Ecosystems Unit is with the Unit Storyline Chart depicted below. The Unit Storyline Chart summarizes a unit phenomenon-based driving question associated with each lesson, what classes will do in each lesson to address the question, what conclusions they will come to, and how they will transition to a subsequent lesson. Download Unit IM and Storyline Chart