add classes and methods lesson

examples/stage0/snippets/classes-methods/Point.java

@@ -0,0 +1,55 @@
+/*
+ * Copyright 2026 FRCSoftware
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+// [pointFull]
+class Point {
+    // [finalFields]
+    // Each Point has its own x and y coordinates, and they never change.
+    private final double x;
+    private final double y;
+    // [/finalFields]
+    // [staticConstant]
+    // Shared by every Point, instead of belonging to just one instance.
+    public static final Point ORIGIN = new Point(0, 0);
+    // [/staticConstant]
+
+    // [constructor]
+    // Sets this Point's coordinates to the given x and y values.
+    public Point(double x, double y) {
+        this.x = x;
+        this.y = y;
+    }
+    // [/constructor]
+
+    // [getters]
+    // Let other classes read the private x and y fields.
+    public double getX() { return this.x; }
+    public double getY() { return this.y; }
+    // [/getters]
+
+    // [plus]
+    // Adds this Point's coordinates to another Point's coordinates.
+    public Point plus(Point other) {
+        return new Point(this.x + other.x, this.y + other.y);
+    }
+    // [/plus]
+
+    // [minus]
+    // Subtracts another Point's coordinates from this Point's coordinates.
+    public Point minus(Point other) {
+        return new Point(this.x - other.x, this.y - other.y);
+    }
+    // [/minus]
+
+    // [norm]
+    // Computes this Point's distance from the origin.
+    public double norm() {
+        double sumOfSquares = this.x * this.x + this.y * this.y;
+        return Math.sqrt(sumOfSquares);
+    }
+    // [/norm]
+}
+// [/pointFull]

examples/stage0/snippets/classes-methods/RobotTracker.java

@@ -0,0 +1,57 @@
+/*
+ * Copyright 2026 FRCSoftware
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+// [robotTrackerFull]
+class RobotTracker {
+    // [mutableField]
+    // Not final, since the robot's position changes as it moves.
+    private Point position;
+    // [/mutableField]
+
+    // [robotTrackerConstructor]
+    // Starts tracking from a given position.
+    public RobotTracker(Point startPosition) {
+        this.position = startPosition;
+    }
+    // [/robotTrackerConstructor]
+
+    // [constructorChaining]
+    // Starts tracking from the origin by default.
+    public RobotTracker() {
+        this(Point.ORIGIN);
+    }
+    // [/constructorChaining]
+
+    // [stateMutation]
+    // Moves the tracked position by delta.
+    public void move(Point delta) {
+        this.position = this.position.plus(delta);
+    }
+    // [/stateMutation]
+
+    // [localVariableChain]
+    // Finds the straight-line distance from the current position to target.
+    public double distanceTo(Point target) {
+        Point diff = target.minus(this.position);
+        return diff.norm();
+    }
+    // [/localVariableChain]
+
+    // [getPosition]
+    // Lets other classes read the current position.
+    public Point getPosition() {
+        return this.position;
+    }
+    // [/getPosition]
+
+    // [useStaticConstant]
+    // Moves the tracked position back to the origin.
+    public void reset() {
+        this.position = Point.ORIGIN;
+    }
+    // [/useStaticConstant]
+}
+// [/robotTrackerFull]

examples/stage0/snippets/classes-methods/Usage.java

@@ -0,0 +1,30 @@
+/*
+ * Copyright 2026 FRCSoftware
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+void main() {
+    // [createAndUse]
+    Point a = new Point(3, 4);
+    Point b = new Point(1, 2);
+
+    Point sum = a.plus(b);
+    System.out.println(sum.getX()); // 4.0
+    System.out.println(sum.getY()); // 6.0
+    System.out.println(a.norm());   // 5.0
+    // [/createAndUse]
+
+    // [accessStaticConstant]
+    System.out.println(Point.ORIGIN.getX()); // 0.0
+    // [/accessStaticConstant]
+
+    // [trackerUsage]
+    RobotTracker tracker = new RobotTracker(Point.ORIGIN);
+    tracker.move(new Point(3, 0));
+    tracker.move(new Point(0, 4));
+    System.out.println(tracker.distanceTo(Point.ORIGIN)); // 5.0
+    tracker.reset();
+    System.out.println(tracker.getPosition().getX()); // 0.0
+    // [/trackerUsage]
+}

src/config/sidebarConfig.ts

@@ -84,10 +84,10 @@ export const sidebarSections: Record<string, SidebarSection[]> = {
                         //     label: 'Loops',
                         //     slug: 'learning-course/stage0/loops',
                         // },
-                        // {
-                        //     label: 'Objects',
-                        //     slug: 'learning-course/stage0/objects',
-                        // },
+                        {
+                            label: 'Classes, Fields, and Methods',
+                            slug: 'learning-course/stage0/classes-methods',
+                        },
                         // {
                         //     label: 'Methods',
                         //     slug: 'learning-course/stage0/methods',