Math · Stage 6

Train-crossing problems (bridge and pole)

A train clears a pole in just its own length — but to cross a bridge it must travel its length PLUS the bridge's. Match the units, add the right distance, then divide by speed.

✦ Math📘 Stage 6 · S6⏱ ~14 min🧒 Ages 10–12★ Free to start

I can solve train-crossing problems.

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Kavi and the Night Express 🦉

Kavi the owl 🦉 watched the night express thunder past the signal pole 🚦. “Whoosh — it cleared the pole the instant its whole body went by, so it only travelled its own length.” Then it roared onto a long bridge 🌉. “Aha — now the front crosses first, but the train isn't clear until the back leaves too. So it travels its own length + the whole bridge! Pick the right distance, divide by speed, and every train puzzle cracks open.”

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What your child will learn

1What distance does the train travel?A train is "past" something only when its back end has gone by. Past a point (a pole or a person) it travels just its own length. Over something long (a bridge, platform or tunnel) it travels its length + that thing's length. Drop each one in the right box →

2Pole vs Bridge — the distance ruleTap each card. The only difference between the two classic train puzzles is how far the train travels. Once you have the distance, both are solved the same way.

3The bridge distance is two partsWatch a 150 m train cross a 250 m bridge. The distance its back end must travel is the train plus the bridge — stacked into one total.

4First decide distance — and match the unitsBefore any dividing, two things must be right: the distance you chose, and the units. Lengths are in metres, so speed must be in metres per second. Try each →

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A peek inside

A train 180 m long runs at 20 m/s. How long does it take to pass a lamp post 💡?

a lamp post is a point, so distance = train length = 180 m; time = 180 ÷ 20

Try this at home: Pole: a 240 m train at 20 m/s passes a pole → how many seconds?

Ready to play and learn?

Start the free interactive lesson, or print the handout for screen-free play.

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Part of Math · Stage 6 · S6 on KAVI Academy — a secular, whole-child learning platform for ages 5–12.