Teacher Guide

Change only the ball's weight: same ramp, same height, same cup. A good answer names at least two things kept the same.

Car E took 4 seconds instead of 5. Each second it went 30 cm, the same as car B, which simply kept going one second longer.

The marble at the far end rolls away and the middle ones barely move. The energy traveled through the line of marbles, which is the whole idea.

About 13 cm, seven tenths of 19. It stops because every bounce turns more of its energy into sound and warmth, until none is left to lift it off the floor. The energy is all still there, as sound and warmth.

Any design that spreads the landing out: a crumple zone, a spring, legs that bend. The good answer says the lander, not the clay, should take in the energy.

Any single change with a way to measure it. The requirement is one change and the same drop.

No. It was moving, so it had energy; it just did not have enough to tip a pin. A strong answer adds that its energy went into rolling and sound.

More grains jump. Tapping harder gives the sound more energy, so it can still shake the wrap from farther away.

Row c arrives as current and becomes light at the lamp; row d arrives as heat and warms the hands. Any row with both forms named is right.

Two bulbs in one loop, one after the other: take one out and the loop opens, so both go dark. Two bulbs each on their own loop from the battery: take one out and the other stays lit. Accept any drawing with clearly closed loops. With one AA battery, two bulbs in one loop may only glow dimly.

No: the toy's battery fills up, so after a while more sun stops adding running time. Any limit with a reason is a good answer.

Any single change, tested the same way. A strong answer predicts before testing.

Store energy in batteries, use wind or water at night, or keep some other source ready. Any workable plan is right.

Two for and two against, each tied to a number. The point is that both sides can be argued honestly.

The sun warms some places more than others; warm air rises and cooler air moves in to take its place. That moving air is wind.

Gravel at the bottom, sand, then fine soil on top: the heaviest pieces settle fastest.

Any third cliff that shares two layers and adds one. The good answer places the new layer in time using the shared ones.

Sugar dissolves and most rock does not, so water would be a bad test of this model. It shows rocks grinding against each other well.

Terraces, a mat of leaves, rocks across the channel. Any idea tested with the same cup of water.

Any practice map with a question a classmate can answer from it.

The plate edge is probably along the coast, because the tall peaks are close to it and the short ones far away. A strong answer says this is a clue, not proof.

Anything that happened after the canyon, placed after it.

Each part of the rope moves up and down in place; the bend travels along it, and that is the energy.

Two drawings, same crest spacing, one twice as tall. Check both labels.

Storm waves are taller, and the extra sand moved grows faster than the height, so beaches change far more in a storm.

Any three steps that reduce harm: fasten shelves, know the safe spot, practice the drill.

Cross braces where they matter most, fewer elsewhere. A drawing and a prediction are the requirement.

Straps plus lips, for example: about the cost of both, with fewer books falling. Any reasoned combination.

48 mm, twice the 10 km wiggle, because 5 km is half of 10 km.

Any animal with three structures suited to cold: thick fur, small ears, wide feet for snow.

Same celery, same water, same color, same time; only the leaves change.

Usually a little sooner or about the same. They used hearing instead of sight, and either way the brain still had to decide.

Arrows from lamp to book to eye; with the lamp off, no arrows, nothing seen.

Any code that both people can read the same way.

Any idea with a reason that really works. Two that do: keep code X's letters and make the pause between letters much longer (pauses are not counted, so it stays as fast as code X), or add a third kind of flash, such as a very long flash, so every letter fits in exactly 2 flashes (3 kinds in 2 places make 9 patterns, enough for 6 letters). Check the count with any fixed-length idea: 2 flashes of only short and long make 4 patterns, too few for the 6 letters.

Their own chain, as long as each link really passes energy to the next.