Designing Your Biology Course

A Practical Guide to Help You with Course Scope & Sequencing

Have you ever found yourself contemplating whether to sequence your course from big to small, or from small to big? Even more, ever considered the order in which material within any given unit should be taught? Maybe your current approach has left your students feeling like the information being taught in the course is disconnected, making it difficult for them to see how everything fits together? Or, maybe your course is cohesive, but you find that some of the units don’t challenge your students enough, while others are too difficult? Whether you’re new to teaching, returning after time away, or a seasoned educator looking for a fresh approach, we’ve created a practical guide to help you plan with purpose and clarity, and provided our scope and sequence for reference. After all, a coherent and intentional scope and sequence is critical. Like all other subjects, information in biology builds—conceptually and practically. Without an intentional progression of information, students may learn facts, but not develop an understanding of how it connects back to them.

Disclaimer

While the purpose of this article is to help you evaluate different approaches to sequencing your high school biology course, and identify that which is most authentic to you, it’s important to note that for us, this topic carries a certain degree of subjectivity. With that being said, while we may not remain entirely objective, we recognize that every educator reading this is as unique as the next; you bring with you different interests, expertise, and experiences; you teach different students, subjects, and grade levels; you teach in different districts and schools; and you may even hold different job titles. As such, what has worked well for us, may not work for you—and that’s okay! In the very least, should you feel that your opinions or experiences differ from ours, we hope this article serves as a catalyst for meaningful reflection, and fosters an even grander dialogue between yourself and your colleges, staff, or even students.

Do You Remember Bloom?

We cannot have an informed conversation about the design and layout of any course without first reviewing Bloom’ Taxonomy—a foundational and well respected learning framework in the world of education, which you are likely already familiar with. Originally created for university examiners in 1956, this framework sought to classify different levels of thinking, but the results, which focused exclusively on learning objectives, made the process of learning seem static. Despite the intended audience being academic theorists, Bloom’s model was adopted by the greater educational community and with that adoption, came many misconceptions. Of these misconceptions, two were most concerning:

1. Frontloading knowledge no longer had a key place in the classroom or in the least, was far less important;

2. The cognitive processes at the bottom where more important (as indicated by size) than the ones at the top and as such, more class time should be devoted to them.

In an effort to address misconceptions such as these, and shift the focus of the framework to a more dynamic view of teaching, learning, and assessing, a team of experts revised Bloom’s taxonomy in 2001. Not only did this revision change the language, but it also placed knowledge below all six cognitive processes, as it was argued that one could not master them in the absence of knowledge—which included factual, conceptual, and procedural knowledge (subject specific), as well as metacognitive knowledge (universal knowledge). Additionally, this revision further emphasized that the size of each step or level—when shown as part of a pyramid—does not reflect importance. Instead, it illustrates a hierarchy of prerequisite cognitive processes which must be mastered before one can engage in the highest order of thinking: creation.

In consideration of these changes, we developed our own reimagined infographic (pictured below) of Bloom’s revised taxonomy—a creation inspired by the Center for Teaching at Vanderbilt University’s graphical representation [1], and the information outlined in Dr. Forehand’s guide to Bloom‘s revised taxonomy [2]:

Now you might be asking: What does this framework have to do with designing and laying out a course? If your goal is to have your students engaging in higher order thinking (deeper learning) by the end of each unit, as well as by the end of the course, using this framework to help you strategically organize the sequence of your course, your unit plans, and even your individual lessons, may be helpful. For example, if you want your students to be able to engage in a critical debate at the end of your gene expression unit, on the ethics of genetically modifying foods, you must first determine what information they need to know in order to effectively do this. Then, you’ll need to figure out how you can help them remember, understand, apply, and analyze said information throughout the unit. Going even further, you might ask yourself what prior information they need/would be helpful for them to know before said unit begins…and now we are back to talking about the scope and sequence of the entire course, not just the unit itself.

We have used this revised framework to create resources that help our students work towards higher order thinking processes as they progress through each unit within our year long curriculum. Further, we have used it to determine the order in which material should be taught, so that students enter each unit with critical prerequisite knowledge.

Big to Small?

When educators hear “big to small” vs. “small to big,” the conversation often centers around the overall course scope and sequence—how we organize biology instruction from the first week of school to the last. While that’s certainly part of it, we believe the conversation is more nuanced. There are two key ways in which “big to small” thinking can inform a general education high school biology course: Across all units (course-level sequencing) AND within each unit (unit-level sequencing).

A "big to small" approach at the course level begins the year by exploring large-scale, interconnected biological systems—such as ecosystems or evolutionary processes—and gradually narrows in on more microscopic and abstract concepts, like cellular function and biochemistry. Advocates of this approach argue that starting with complex systems (for example, an exploration of the dynamic relationship between the wolves and moose on Isle Royale) invites students to engage in meaningful inquiry. Faced with real-world phenomena, students are naturally driven to ask why and how—questions that lead them to uncover the molecular and cellular mechanisms behind their observations. One high-level curriculum administrator from a major urban district even suggested that this sequencing cultivates the kind of higher-order thinking that Darwin engaged in when exploring the Galapagos Islands. In other words, it fosters a process of observing natural phenomena and patterns, then working backwards to understand the mechanisms behind them. Did this administrator have a point?

At the unit level, a “big to small” approach begins with a driving question or the exploration of a compelling, real-world phenomenon—a tangible event or problem that engages students and sparks curiosity. From there, instruction dives into the core information, ideas, concepts, and practices necessary to understand and explain said phenomenon. Advocates for this approach argue that such a sequencing increases student engagement, retention, and sense-making, because students aren’t just learning information in a vacuum—they’re using it to solve problems that matter and explain the world around them. Unfortunately, in our experience, finding traditional phenomena that are relevant to students and maintains their interest throughout the course of a given unit is difficult, in the context of biology, that is.

Small to Big?

Opposite the “big to small” approach is the “small to big,” the more traditional of the two. A course sequenced in this way typically begins with microscopic concepts such as macromolecules and cellular biochemical processes, before progressing to larger-scale concepts like genetics, ecosystems, and evolution. Proponents of this approach argue that students must master foundational knowledge before they can meaningfully apply or transfer it. The rationale is that students need to understand the building blocks before they can comprehend the large-scale, interconnected systems. After all, how can a student truly grasp natural selection if they haven’t yet learned how traits are inherited or how mutations occur?

Can You Mix Them?

In the sense that your course-level sequence could follow a traditional small-to-big approach, while you frame instruction within each unit around big, compelling phenomena, then yes—you can mix the two (this is actually what we have done). However, any alternative “blending” of often [always] results in a course that feels disjointed and disconnected to the students who are learning the material for the first time. Unfortunately, many traditional textbooks, and by extension many biology courses built around them, are inadvertently structured in this way: one chapter on mitosis, another on enzymes, then a sudden shift to ecology, with little connection made between them. As a result, students struggle to see how the content fits together, or how it applies to the world outside the classroom.

Our Approach

As was previously mentioned in the disclaimer, we have not taken an entirely objective position on this subject matter. However, we want to be very clear before we proceed to discuss our approach: we do not believe that curriculum should be one-size-fits-all, we are proponents of Universal Design for Learning (UDL), and still, we stand firmly behind our decision to sequence our high school biology course in the way that we have.

If our approach resonates with you and you choose to implement our curriculum with fidelity—great!

If you use it as a foundation from which you build a course that reflects your own style or your students’ unique needs—we are here for it!

If this article simply sparks an idea or fosters a dialogue that leads you to create something entirely original—we say go for it!

Now that we have cleared that up, lets take a look at our course scope and sequence, and the reasons for which we chose the approach and structure we did!

Overview

Our year-long curriculum is designed to engage students through the use of hands-on, interesting, and relevant learning material. With the exception of “The Chemistry of Life,” each unit is centered around a bioethical dilemma, providing students and teachers the flexibility to explore the material's real-world applicability and significance together.

Research and experience show that anchoring a given learning unit with a driving phenomenon improves student learning outcomes. Unfortunately, we have found that traditional phenomena don’t fit well within the typical high school biology classroom; and storylines can feel restrictive, cause the units across the course feel disconnected, and make the material feel largely irrelevant to many students (especially those in marginalized communities). Our solution has been to replace traditional phenomena with bioethical dilemmas to boost engagement, foster a better understanding of the interconnectedness of biological concepts, and make the content more relevant and meaningful. More information on how our curriculum aligns with NGSS, and the importance of phenomena-based learning, can be found here. For clarity, we have included this model below, which illustrates how each of our units are laid out:

Course Scope & Sequence Overview

While a more detailed breakdown of each unit appears in order within the “Detailed Course Scope and Sequence” section of this article, we have included this table for your convenience:

SEMESTER ONE Biology A	SEMESTER TWO Biology B
Unit 1: The Chemistry of Life	Unit 4: Biochemical Systems
Unit 2: Nucleic Acids	Unit 5: Genetics
Unit 3: Cells	Unit 6: Diversity of Life

Justification for Sequencing

Our current scope and sequence reflects years of research, classroom experimentation, and continuous adjustment in an effort to improve learning outcomes for our students. Key reasons for the chosen order include:

1. From Small to Big (Course): Beginning with the smallest, microscopic concepts creates a solid foundation from which students can more quickly and deeply understand new material as it is presented. Answering questions becomes less about teaching new information, and more about reflecting on previously learned information, thereby reinforcing important material and allowing students to draw more meaningful connections as the course progresses.

2. From Big to Small (Learning Units): As was previously mentioned, all of our units begin with a driving investigation or the examination of a bioethical dilemma from which all learning in said unit is anchored. The learning material within the units themselves are either sequenced hierarchically from small to big, or from the start of a system to its end (discussed further below).

3. Systems Thinking: To the fullest extent possible, each unit is designed to highlight biological systems. For example, Unit 1 moves from atoms to molecules to macromolecules (a hierarchical system), while Unit 4 traces the flow of energy and nutrients from plants through animals (a complex system).

4. Separating Nucleic Acids and Genetics: Understanding nucleic acids—DNA replication, protein synthesis, and mutations—is not only essential for grasping genetics (Unit 5), but also for understanding cells and cell processes (Unit 3); as well as biochemical reactions and digestion (Unit 4). Further, it is a natural extension from macromolecules (Unit 1), which touches on DNA and proteins.

5. Separating Cell Division Processes: Mitosis and meiosis are separated to avoid confusion, and to better align them with related content. Mitosis is taught with somatic cell structure, while meiosis is covered in the genetics unit to reinforce inheritance concepts.

6. Planning for Disengagement: As the year progresses, student motivation wanes and disengagement increases. Placing more abstract, challenging topics early in the year, and more easily understood ones towards the end, increases learning and performance outcomes. Luckily, this naturally happens when you go from small to big across a course!

Detailed Course Scope & Sequence

Unit 1: The Chemistry of Life

ABSTRACT	This introductory unit is intended to provide students with the foundational knowledge required in order to deeply understand larger biological concepts including DNA and protein synthesis, cell structure and function, biochemical reactions, genetics, nutrient flow within ecosystems, etc. During the introduction, students will engage in an exploratory activity in which they dissect and examine the composition and physical properties of various living/once living things (i.e. fruits, vegetables, lettuce, dead insects, etc.).
DURATION	5 weeks
STANDARDS	HS-PS1-1; HS-PS1-2; HS-PS1-3; HS-PS1-8; HS-LS1-6
DRIVING INVESTIGATION	Given that the first unit is heavily rooted in chemistry, the driving phenomena will be a more traditional laboratory investigation in which students dissect a food item, then develop questions about its structural and/or chemical makeup.
LEARNING SECTIONS	Atoms The structure of atoms; ions and isotopes; interpreting and using the Periodic Table of Elements
	Molecules Differentiating between molecules & compounds; electronegativity; types of intra- and intermolecular bonds/forces; mixtures and solutions
	Macromolecules Unique properties of carbon; the building blocks of macromolecules; the structure, properties, functions, and significance of each of the four classes of macromolecules

Unit 2: Nucleic Acids

ABSTRACT	This unit builds on the previous one, and provides students with an in-depth look at the process by which the information encoded within our genes gets expressed, and the role that DNA plays in the variances seen across all living organisms. This unit will begin with a class wide examination of one of the following bioethical dilemmas. During the introduction, students will assess what they already know (or think they know); receive a brief introduction to the topic and some of its implications via a short video, reading, or exploratory activity; compile a collective list of questions they would like to see answered; and determine what they need to understand more fully, in order to have a productive debate.
DURATION	5 weeks
STANDARDS	HS-LS1-1; HS-LS3-1; HS-LS3-2
DRIVING INVESTIGATION	Gene Editing in Living Organisms (CRISPR) GMOs in Our Food (GM Crops) GMO in Medical Treatments (Using Viruses to Cure Cancer)
LEARNING SECTIONS	DNA Synthesis The structure and primary function of DNA; the reasons for which DNA replicates; the process by which DNA replicates (including the enzymes involved); biological mechanisms that ensure the process remains effective and efficient
	Gene Expression The structure and primary functions of RNA; structural and functional groups of proteins; transcription of DNA; translation of RNA; key enzymes involved in gene expression
	Mutations Causes of mutations (including mutagens); types of mutations (point mutations vs. chromosomal); germline vs somatic mutations; mutations in gene regulation; consequences and importance of mutations

Unit 3: Cells

ABSTRACT	This unit builds on the previous two by examining the structure and overall function of cells, cell division, and cell differentiation. It allows students to see the role that carbohydrates, lipids, and proteins play in the structure of living organisms, and the role that DNA plays in cell differentiation—a process responsible for much of the complexity seen across living organisms on this planet. This unit will begin with a class wide examination of one of the following bioethical dilemmas. During the introduction, students will assess what they already know (or think they know); receive a brief introduction to the topic and some of its implications via a short video, reading, or exploratory activity; compile a collective list of questions they would like to see answered; and determine what they need to understand more fully, in order to have a productive debate.
DURATION	5 weeks
STANDARDS	HS-LS1-1; HS-LS1-2; HS-LS1-4
DRIVING INVESTIGATION	Having Children to Save Their Siblings (Bone Marrow Transplant) GMOs in Our Food (GM Crops)
LEARNING SECTIONS	Cell Structure & Function The Cell Theory; multicellular vs. unicellular; eukaryotic vs. prokaryotic cells; cell structures and their functions; comparing and contrasting different eukaryotic cells (animal/plant/fungi)
	The Cell Cycle Somatic cells; the purpose and importance of the cell cycle; phases of the cell cycle (G1, S, G2, and M Phase); key events in mitosis; cell division in animal vs. plant cells; regulation of cell growth and division (cancer)
	Cell Differentiation The importance and role of cell differentiation and specialization; specialized animal/plant cells and their functions; stem cells (embryonic vs. somatic); regulation of cell differentiation; cell communication in multicellular organisms

Unit 4: Biochemical Systems

ABSTRACT	This unit builds on the previous three by closely examining the processes by which macromolecules are made available to us, the mechanisms by which we digest them and once digested, how our cells transform them into energy and other necessary molecules intended for different uses throughout the body. This unit will begin with a class wide examination of one of the following bioethical dilemmas. During the introduction, students will assess what they already know (or think they know); receive a brief introduction to the topic and some of its implications via a short video, reading, or exploratory activity; compile a collective list of questions they would like to see answered; and determine what they need to understand more fully, in order to have a productive debate.
DURATION	6 weeks
STANDARDS	HS-LS1-2 ; HS-LS1-3; HS-LS1-4; HS-LS1-5; HS-LS1-6; HS-LS1-7; HS-LS2-5
DRIVING INVESTIGATION	Concerns in the Health & Wellness Industry (An Elitist Community) When Personal Beliefs Endanger a Child’s Health (The Vegan Baby) Does “Healthy” Have a Look? (Gut Bacteria and Digestion)
LEARNING SECTIONS	Photosynthesis (Plants) Types of photosynthetic organisms; specialized photosynthetic cells and important organelles; light dependant and light independent reactions; factors affecting photosynthesis; role and importance of it in ecosystems
	Digestion & Membrane Transport (Animals) Homeostasis; catabolism; mechanical vs. chemical digestion; exoenzymes; digestive organs; digestive pathways for each class of macromolecule; nutrient absorption; factors affecting digestion and absorption; cell membrane structure; passive vs. active transport
	Biosynthesis & Bioenergetics Purpose and importance of cellular respiration; mitochondria; glycolysis, Krebs cycle, and electron transport chain; aerobic vs. anaerobic respiration; ATP; role and importance of biosynthesis; anabolism; carbohydrate, lipid, protein, and nucleic acid synthesis

Unit 5: Genetics

ABSTRACT	This unit builds on the previous four by closely examining the processes by which traits are passed down from parents to offspring, the role heredity has in biodiversity and inevitably, why genetic diversity is so important for the success of a species. This unit will begin with a class wide examination of one of the following bioethical dilemmas. During the introduction, students will assess what they already know (or think they know); receive a brief introduction to the topic and some of its implications via a short video, reading, or exploratory activity; compile a collective list of questions they would like to see answered; and determine what they need to understand more fully, in order to have a productive debate.
DURATION	5 weeks
STANDARDS	HS-LS2-2; HS-LS2-8; HS-LS3-1; HS-LS3-2; HS-LS3-3; HS-LS4-2
DRIVING INVESTIGATION	Predictive Genetic Testing (To Test or Not to Test?) Using DNA Technology in Forensics (Ethical Considerations) Reproductive Cloning (Is Cloning Ethical?) IVF (Ethical Dilemmas in IVF)
LEARNING SECTIONS	Meiosis Sexual reproduction; gametogenesis and the phases of meiosis; events that lead to genetic diversity (crossing-over, segregation, and random assortment); nondisjunction; unequal cytoplasmic division of eggs
	Patterns of Inheritance Mendelian genetics (monohybrid and dihybrid dominant/recessive inheritance patterns); non mendelian genetics (codominance, incomplete dominance, and sex-linked inheritance patterns); the basics of polygenic inheritance; non-nuclear genetics; epigenetics
	Pedigrees Interpreting pedigree symbols; analyzing inheritance patterns (autosomal dominant, autosomal recessive, sex-linked); predicting inheritance (genetic counseling); creating pedigrees

Unit 6: Diversity of Life

ABSTRACT	This unit builds on all that has been learned in the previous course units and to some extent, is a near direct extension of what was covered in the previous unit. Unit 6 closely examines the flow of energy through ecosystems, important types of interactions that exist within ecosystems, the interconnectedness and important role each organism within a shared ecosystem has on the success of another, and how all of this has contributed to the biodiversity we see. This unit will begin with a class wide examination of one of the following bioethical dilemmas. During the introduction, students will assess what they already know (or think they know); receive a brief introduction to the topic and some of its implications via a short video, reading, or exploratory activity; compile a collective list of questions they would like to see answered; and determine what they need to understand more fully, in order to have a productive debate.
DURATION	6 weeks
STANDARDS	HS-LS1-5; HS-LS2-1; HS-LS2-2; HS-LS2-3; HS-LS2-4; HS-LS2-6; HS-LS2-7; HS-LS2-8; HS-LS4-1; HS-LS4-2; HS-LS4-3; HS-LS4-4; HS-LS4-5; HS-LS4-6
DRIVING INVESTIGATION	Human Population Control/Regulation (Are There Ethical Policies?) Human Overconsumption of Resources (Ethics of Regulation) Emerging Infectious Diseases (Ethical Implications that May Arise) Artificial Selection (Is Artificially Selecting for Consumption Ethical?)
LEARNING SECTIONS	Ecosystems Biotic vs. abiotic factors; levels of ecological organization; niches; community interactions (competition, predation, symbiosis); carrying capacity; invasive species; ecological succession; the impact of weather and climate on ecosystems; the greenhouse effect
	Cycles of Matter & Energy Flow The carbon and nitrogen cycles; the relationship between these cycles, global warming, distribution of water and food across this planet, and energy flow through ecosystems; producers vs. consumers; food chains and food webs; trophic levels; biomass pyramids; the 10% rule
	Evolution Misconceptions surrounding evolution; evidence of evolution; Darwin and The Theory of Natural Selection; environmental pressures; adaptations and survival of the fittest; population genetics; genetic drift; descent with modification; speciation Interpreting pedigree symbols; analyzing inheritance patterns (autosomal dominant, autosomal recessive, sex-linked); predicting inheritance (genetic counseling); creating pedigrees

Conclusion

As you consider how best to structure your high school biology course—whether from big to small, small to big, or somewhere in between—remember that your goal isn't just to cover content, but to cultivate curiosity, connection, and a deeper understanding of the material being taught. A strong scope and sequence is not just a map of topics; it’s a story arc that helps students make sense of the natural world and their place in it.

The way you structure that story matters. Beginning with big ideas can spark inquiry and frame learning in ways that feel authentic and engaging, while beginning your course with small, foundational concepts can provide students with the prerequisite knowledge they need in order to build deeper understanding later in the course. Both have value—but neither should be implemented blindly. The key is to design intentionally, with your students, context, and learning goals in mind.

Above all, we hope this guide helps you approach planning not as a rigid formula to follow, but as an opportunity to think deeply about what your students need in order to thrive. Teaching is an evolving practice. Each year brings new challenges, new students, and new insights. Whether you adopt our scope and sequence, only parts of it, or use it as a springboard for your own ideas, we’re glad to be part of your journey toward more purposeful, intentional instruction!

References

[1] Armstrong, P. (2010). Bloom’s Taxonomy. Vanderbilt University Center for Teaching. Retrieved [2023, December 31] from https://cft.vanderbilt.edu/guides-sub-pages/blooms-taxonomy/

[2] Forehand, M. (2011, December 12). Bloom’s Taxonomy: Emerging perspectives on learning, teaching, and technology. University of Georgia. Retrieved from https://cft.vanderbilt.edu/wp-content/uploads/sites/59/BloomsTaxonomy-mary-forehand.pdf