Countdown to Science 4.3 and 4.4

A student records observations of the appearance of her shadow during different times of the day. The student notices that the size and direction of her shadow looks different in the morning compared to the afternoon. The changing appearance of shadows throughout the day provides evidence of what natural phenomenon?

• The Earth rotates around the Sun every 24 hours.

• The Earth rotates around the Sun every 365 days.

• The Earth rotates on its axis every 24 hours.

• The Earth rotates on its axis every 365 days.

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5.8C

The diagram below is an overhead view of a car and its side-view mirrors.

Which diagram shows the mirrors positioned correctly so the driver can see the bicycle behind the car?

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5.6C

During which stage in the life cycle of the apple tree are seeds produced?

• Germination of the seed into a sprout.

• Growth of a young plant into a mature plant.

• Pollination of the apple blossom.

• Ripe apples fall to the ground.

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3.10

Below is a picture of a lava lamp. Inside is a clear liquid and a colored wax. The light atthe bottom of the lamp heats the wax closest to the light. As the wax is heated, its densitydecreases and wax globules rise to the top. As the wax cools, its density increases and the wax globules fall back down to the bottom. Besides density, what other physical property of the wax is important for the lava lamp to work?

• Solubility – the wax must be insoluble in water

• Electrical conductivity – the wax must conduct electric energy

• Magnetism – the wax must be magnetic

• Thermal insulation – the wax must be able to insulate thermal energy

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5.5.A

The webbed foot of a duckling and the webbed foot of a frog are shown below.

How do webbed feet benefit ducklings and frogs?

• They help the organisms hunt and eat their food.

• They help the organisms protect themselves from predators.

• The help the organisms detect the world around them.

• They help the organisms swim in their aquatic habitat.

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5.10.A

A student collects a mixture of sand and sea shells during a trip to the beach. What would be the best method to separate the shells from the sand?

• Use a sieve to separate the shells from the sand.

• Use a magnet to collect the sand particles.

• Dissolve the sand in water and filter out the shells.

• Use a hammer to crush the shells.

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5.5B

A student builds the circuit below during science class and observes that the circuit doesnot work. None of the lightbulbs turn on and the bell does not ring.

What change needs to be made to the circuit for it to work?

• Remove the bell because a circuit cannot contain both lightbulbs and bells.

• Add a switch to the circuit because a circuit needs a switch to operate.

• Flip one battery because they need to be connected negative end to positive end.

• Shorten the wires because the wires are too long for the circuit to work.

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5.6.B

Texas is the largest emitter of carbon air pollution into the atmosphere in the United States. These carbon emissions come from construction sites, manufacturing plants, oil refineries, power plants and vehicles. The emissions are not only bad for humans to breathe, but the air pollution enters the local water supplies and soil. Which statement below is NOT a possible effect on the ecosystems of Texas caused by this air pollution?

• Children can develop serious health issues because of breathing in pollution from the air.

• Air pollution can decrease the amount of vegetation that can grow in an area.

• Air pollution causes global climate change, which improves the ecosystem forplants and animals.

• Animals can consume contaminated water sources, leading to health problems and even death.

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5.9.C