How do I school a reining pattern without making my horse anticipate?

Schooling a pattern without creating anticipation requires treating the pattern as a collection of individual maneuvers connected by transitions rather than as a fixed sequence that is always practiced from beginning to end in the same order. Anticipation develops specifically from predictability — when the horse learns that a specific maneuver always follows a specific cue in a specific location, it begins to execute that following maneuver before the rider asks, which is the definition of anticipation. Remove the predictability at every level: sometimes circle left without following with a lead change, sometimes make a lead change without following with a circle in the new direction, sometimes stop without rolling back, sometimes spin fewer revolutions than usual and sometimes more. The horse that cannot predict what follows a given maneuver must wait for the rider's specific instruction rather than executing from memory. Work the maneuvers in isolation as the majority of practice time — circles practiced without lead changes, stops practiced without rollbacks, spins practiced without the immediately preceding or following elements — so that no maneuver automatically triggers the expectation of another in the horse's mind. When lead changes are practiced, vary the location: sometimes in the center as the pattern requires, sometimes elsewhere in the arena, sometimes not at all during a given circle session. When stops are practiced, vary the rundown length and the location of the stop so the horse cannot use speed buildup or arena position as the cue to stop rather than the rider's aid. The horse whose training has never allowed it to predict what comes next is the horse that arrives in the show pen waiting for the rider's instruction — which is precisely the responsiveness that correct scores and correct performance require.