The Wake-Up Machine
Twins Rosa and Leo build a chain-reaction machine to wake Dad up on his birthday. It takes many tries, and a lot of dominoes.
Dad's birthday was on Saturday, and twins Rosa and Leo had a plan. Not a cake, not a card, but a machine. A wake-up machine that would ring a bell beside his bed, all by itself.
"It's called a chain reaction," said Rosa, who had seen one in a library book. "One thing knocks into the next thing, which knocks into the next thing, all the way to the end."
They started in the hallway on Thursday after school, with blocks, dominoes, a toy car, a ball, a long cardboard tube and a little bell from the Christmas box.
Here was the plan. Step one: push the first domino. Step two: a line of dominoes falls. Step three: the last domino tips the toy car down a ramp made of a book. Step four: the car hits a ball. Step five: the ball rolls through the tube. Step six: the ball knocks over a tower of blocks. Step seven: the top block falls onto a ruler, which flips up and rings the bell.
They called it test one. Leo pushed the first domino. Click, click, click, click... then nothing. One domino was too far from the next.
"The gaps need to be smaller than the domino is tall," said Rosa. They moved them closer.
Test two. The dominoes fell beautifully. The car rolled down the ramp, hit the ball, and the ball rolled the wrong way and under the radiator.
Test three. The ball went into the tube, but the tube was too flat. The ball stopped in the middle. Leo had to tip the tube up on a stack of books so it sloped downhill.
Test four. Everything worked until the tower of blocks, which fell sideways instead of forwards and missed the ruler completely.
By test nine, it was getting dark, and the cat had walked through the dominoes twice. Leo flopped onto the carpet. "This is impossible," he groaned.
Mum looked in. "How many tries have you had?" she asked. "Nine," said Rosa. "Well," said Mum, "that means you've found eight things that don't work, and fixed them. That's what engineers do all day."
They tried again on Friday, after school. Test ten. Test eleven. Test twelve. Every time, something small went wrong, and every time, they fixed it.
Then came test thirteen. Click, click, click went the dominoes. Down went the car. Bump went the ball, through the tube, into the tower. The top block toppled onto the ruler. The ruler flipped up. Ding!
They screamed so loudly that Mum came running. Then they had to set up the whole thing again in Dad's room, very, very quietly, early on Saturday morning.
At seven o'clock, Rosa pushed the first domino. Click, click, click. Roll. Bump. Clatter. Ding!
Dad opened one eye. Then the other. He sat up and looked at the trail of fallen dominoes, the car, the tube, the blocks, and two grinning faces.
"Happy birthday!" shouted Rosa and Leo.
"That," said Dad, "is the best alarm clock I have ever had." Then he looked at the clock. "Although on Saturdays, maybe next time it could ring at nine?"
⭐ The End ⭐
💬 Talk about it
- What is a chain reaction?
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When one thing knocks the next, all the way to the end. - What was the last thing in the machine?
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A bell. - Which test finally worked?
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Test thirteen. - What did Mum say about the tests that failed?
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They had found things that did not work and fixed them, like engineers.
