Children create patterns with two alternating elements (red-blue-red-blue or clap-stomp-clap-stomp). AB patterns are the simplest repeating patterns and develop pattern thinking.
Use two colors of blocks or beads. Act out patterns with movements. Extend prepared AB patterns with blocks or paper shapes.
Creating a different pattern instead of repeating AB. Adding elements randomly rather than maintaining the pattern rule.
A pattern is a sequence that follows a rule — something that repeats in a predictable way. The simplest possible rule uses just two different things that take turns: A, B, A, B, A, B... This is called an AB pattern. The "A" and "B" are just labels for two different items — they could be colors, shapes, sounds, or movements. Red-blue-red-blue is an AB pattern. Clap-stomp-clap-stomp is an AB pattern. Big-small-big-small is an AB pattern. The specific items don't matter; what matters is the rule: two things, alternating, forever.
The key idea is that a pattern is about what comes *next* being *predictable*. If you know the rule is AB, and you see red-blue-red, you already know the next one must be blue — even before you see it. This is the first taste of mathematical thinking: using a rule to make a prediction. When you extend an AB pattern by adding the next block, you're not guessing — you're applying the rule. That sense of "I know what comes next" is what makes patterns satisfying and useful.
To create your own AB pattern, pick two different things — two colors of beads, two body movements, two sounds — and take turns with them, repeating. The hardest part at first is staying consistent: once you pick your two items, only those two, and they must always alternate. A common slip is adding a third item or repeating one item twice. If your pattern is circle-square-circle-square and you accidentally place circle-circle, the pattern rule has been broken. Notice it, name it, fix it — that self-correction is the same mathematical reasoning you'll use to check your work for the rest of your life.
AB patterns also live in the world around you — stripes on clothing, the black and white keys of a piano, alternating floor tiles, the beat in simple songs. Once you start noticing AB patterns, you see them everywhere. And recognizing that two very different-looking things (one in colors, one in sounds) can share the same underlying AB rule is your first experience with mathematical abstraction: the idea that the same pattern can show up in many different forms.