A student blocks the outlet of a bicycle pump with a finger and pushes the handle partway down. The trapped air takes up less room but does not leak out. What best explains this?

Being attracted to a magnet is a property that can be used to tell an iron sample apart from an aluminum sample.

A student stirs colored drink powder into a glass of water. The powder can no longer be seen, but the water is colored and tastes sweet. What happened to the powder?

Ocean water is poured into a shallow pan and left on a sunny windowsill for two days. The pan is dry, and a white solid coats the bottom. What happened?

A pot of soup warms on the stove. A few minutes later, someone in the next room can smell it. What is the best explanation for the smell traveling?

A student measures 250 grams of water into a jar, adds 20 grams of drink powder, and screws the lid on tight. After stirring, the powder has dissolved. What is the total weight of the water and powder now?

A sealed bag holds 90 grams of ice. The bag sits on a counter until every piece of ice has melted, and nothing leaks out. What do the contents of the bag weigh now?

A flat basketball is pumped up with air. The ball gets firmer and firmer, even though nothing anyone can see is going into it. What best explains why the ball becomes firm?

A gray sample is tested three ways. It looks shiny when polished, it lets a bulb light up in a circuit, and a magnet does not pull on it at all. Which material is the sample?

A company is choosing a material for a soup pot handle. One end of each sample is heated for 5 minutes, and the temperature rise at the far end is measured. Copper: 38 degrees. Steel: 22. Plastic: 6. Wood: 3. Which material should the handle be?

Two white powders are stirred into separate cups of water. Powder A spreads through the water and cannot be seen. Powder B settles in a layer on the bottom. Which property is being tested?

Steel paper clips are stirred into a bowl of uncooked rice. A student holds a magnet over the bowl and lifts every clip back out, unchanged. What does this show?

A student stirs a spoonful of baking powder into a cup of lemon juice. The mixture fizzes hard, bubbles of gas rise for a minute, and the cup feels cooler. What do these signs show?

A student in Chile lets go of a ball and it falls to the ground. A student in Canada does the same, and the ball falls to the ground there too. What do these observations show about gravity?

Two balls are the same size, but one is much heavier. Dropped from the same balcony at the same moment, they hit the ground at nearly the same time. What claim does this support?

A hawk eats a mouse, and that mouse had been eating grass seeds all morning. Where did the energy in the hawk's meal originally come from?

A maple leaf falls onto the forest floor. Over the winter, worms, insects, and other decomposers break it down. What happens to the matter that was in the leaf?

A rabbit eats clover in a meadow. Later, the rabbit's waste drops on the ground, and worms and other decomposers break it down in the soil. Where does the matter in that waste end up?

A sealed jar holding water and a strip of iron weighs 400 grams. Weeks later the strip is coated in reddish-brown rust, and the jar has never been opened. What does the sealed jar weigh now?

A student pours 100 grams of vinegar onto 10 grams of baking soda in an open cup. The mixture fizzes hard, and afterward the cup and its contents weigh less than 110 grams. What best explains the missing weight?