Teaching formal logic has been mostly abandoned, in my lifetime. If we brought it back, I believe schools would restore an essential tool in building a more civil society. For the past five years, I've done this in my classroom by applying the classical model of learning. Increasingly supported by evidence from cognitive science about how we learn, the classical model moves through three stages of learning: (1) grammar, (2) logic, and (3) rhetoric.
The grammar stage is about learning the language of a domain. Students need a rich knowledge base in order to engage in higher-order thinking. In this approach, the primary emphasis during the early phases of a curriculum is on building a broad knowledge base of relevant vocabulary and information in the domain.
The logic stage is about questioning and critiquing ideas and about how to use the language. The most important component of this stage is the deliberate interaction with opposing ideas, stripped of all emotion, to reveal the nuts and bolts of a claim. This stage allows for the critique of ideas from diverse perspectives and provides an objective frame of reference to evaluate the quality of claims as supported by evidence. Consequently, in this stage, emphasis is placed on how to develop an argument without being argumentative and how to detect common false lines of reasoning.
Finally, the rhetoric stage is about expressing oneself elegantly and persuasively. By this stage, students have developed a broad knowledge base and a respect for the hard work required to engage in good reasoning, so I find that they perform this phase with humility and depth of knowledge.
The classical model can be applied at the school level without radically altering your state curricula. I propose three steps that could be immediately implemented, within state mandates:
Step 1: Clarify the essentials of your school's guaranteed and viable curriculum.
If your school is "guaranteeing" that all students will complete their education in your school with all the standards from your state, it is not viable. Doug Reeves proposes you consider three criteria for determining "power standards" (or essentials): endurance (relevant throughout life), leverage (applicable across domains), and essentiality (sequentially important). I think these provide a good lens through which you can begin the discussion at each grade or in each discipline of what the essential "grammar" ought to be.
Once you have done this, keep in mind the goals for a grammar stage when observing instruction. For example, lower-order questions tend to be devalued in most teacher evaluation models. But at the grammar stage, these types of questions help build the foundation from which students can acquire increasingly complex knowledge. I encourage recasting so-called "lower-order" questions or skills as "essential order" questions or skills. Doug Lemov makes a similar argument in this blog post, where factual knowledge, practiced for recall and retrieval, provides the fuel that powers the higher parts of Bloom's pyramid. (See the "Bloom's Delivery Service" image.)
Step 2: Go deep and engage critique.
As students demonstrate mastery of a broad and accurate knowledge base, educators must work together to ensure that learners interact with similar concepts at increasing depth and through serious critique of ideas (logic). Integrating both spiraled curriculum and modeled criticism will foster students' sense that (a) there is always more to learn about a subject, and (b) criticism is useful and can be done civilly. In today's divisive political climate, this second element is of the utmost importance.
Step 3: Take, and state, your position.
As a culmination of these learning experiences, students take a position on topics of study, based on thorough critique and consideration of alternative viewpoints (rhetoric). These performances act as assessments of and for learning, providing a rich set of authentic achievement data while also giving students the tools to engage in a civil society that will have disagreements.
Learning is a process by which students build up accurate understandings, acknowledge their own assumptions and misconceptions, engage civilly with those who hold different perspectives, and seek to improve their learning by getting ever closer to truths. At its core, that's what the classical approach is all about. What's more, by moving learning through these three stages, we can restore the necessary skills of civil argumentation that are part of a vibrant republic. I encourage all readers to consider applying this classical model of an intentional grammar stage, logic stage, and rhetoric stage to the design of their curricula; it will equip our students with tools for learning and a comfort with debate that seems to be lacking today.