The story in three lines. Tickwell's town clock loses eight minutes an hour, and the bread burns. Inkling wants to push the hands, but Tock says to check the clock against a beat you trust first. With Inchy's measuring and Stax's bars, the children find the pendulum weight has slid down, slide it back up, and only then set the hands.

One question to ask. "Why didn't pushing the hands fix it?" Pushing the hands fixes the time for a moment. Fixing the beat fixes it for good. If your child says "because the weight slid", ask how they knew.

One thing to do at the table. You need a string about as long as your arm, a small weight (a key, a nut, a spoon tied on), and any clock with a seconds hand. Hold the string still at the top and let the weight swing. One of you counts swings; the other watches the seconds. How many swings in one minute? Now make the string shorter and count again. Then longer. Which way gives more swings?

The grown-up layer. A pendulum's swing time depends on its length, not on how heavy the weight is or how far it swings (for small swings). That is why pendulum clocks are adjusted by moving the weight up or down the rod. The time for one swing grows with the square root of the length, so a pendulum a third longer swings about a seventh slower. You don't need any of this. "Is it the hands, or is it the beat?" is the whole idea.

Let your child tell the story back in their own words first. Telling it back is how the tick-weight goes on the belt.