Leap Science

Lamar is studying water quality in his science class. He learns that salt water is seeping into his neighboring town’s water supply and makes the water dangerous to drink. Lamar’s teacher challenges his class to investigate ways to identify salt water without tasting it. Part A: Lamar has one glass of pure water and one glass of salt and water. The two liquids look exactly alike. What investigation can Lamar perform, without tasting the water, to find out which glass contains the salt water?

• Lamar couldn’t do it. A chemical change has taken place.

• Lamar could evaporate the water to see which cup leaves salt behind.

• Lamar couldn’t do it. It is not possible to identify clear liquids without tasting them.

• Lamar could shine a light into the water and check for salt conductivity.

Tags

NGSS.MS-PS1-2

Gravity Keith’s class has been learning about the effects of Earth’s gravity. His teacher challenges his class to imagine that tunnels are dug into the earth. The teacher draws the diagram below and asks the students to think about what would happen if a red ball were released at the entrance of a tunnel. If a small ball, represented by the red dot in the image to the left, is held just above the tunnels, which path (path A, path B, path C, or path D) would it follow when released? Select the best claim Keith could make about the path the ball would take.

• The ball would follow path A because gravity would pull it to the center of the earth.

• The ball would follow path B because gravity would pull the ball down the tunnel at a slant.

• The ball would follow path C because it would be trapped in the earth’s orbit.

• The ball would follow path D because gravity is a force that pull objects down.

In science class, Marvin studies the effects of mixing substances together. Marvin and his partner measure and collect 450 mL of warm water and 50 mL of salt in a large, glass beaker. They measure the mass of each substance and record the results in the table below. Part A: Marvin and his partner measured the mass of a large, glass beaker. They mix the two substances together in the beaker. They observed a slight color change in the water and that much of the salt disappeared after mixing the two substances. Then, they measured the mixture and subtracted the mass of the beaker so they could record the mass of the substances after they mixed them together. Which estimate is the mass of the mixture?

• 450 grams

• 909.2 grams

• 454.6 grams

• 445.4 grams

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

In science class, Marvin studies the effects of mixing substances together. Marvin and his partner measure and collect 450 mL of warm water and 50 mL of salt in a large, glass beaker. They measure the mass of each substance and record the results in the table below.
Part B: Which statement best explains Part A?

• The water was warm and made some of the salt dissolve. When salt dissolves, it loses its mass.

• Marvin and his partner mixed the water and the salt. This made the mass of both substances double.

• The water was warm and made some of the salt dissolve. Both substances lost a little mass because they were mixed together.

• Marvin and his partner combined the water and the salt. The total mass of each substance did not change even though they were mixed together.

Tags

NGSS.MS-PS1-5

Why do we have leap years?

• To correct for the Earth's rotation speed

• To adjust for the Earth's orbit around the Sun not being exactly 365 days

• To make up for lost time over centuries

• To align the calendar year with the lunar year

What is a leap year?

• A year with 366 days

• A year with 364 days

• A year with 365 days

• A year with 367 days

What is the primary reason for adding an extra day in a leap year?

• To correct the calendar for Earth's axial tilt

• To adjust for the Earth's orbit around the Sun being approximately 365.25 days

• To synchronize with the lunar calendar

• To account for the Earth's slowing rotation

Which of the following is a leap year?

• 1900

• 2000

• 2100

• 2200

How often does a leap year occur?

• Every 2 years

• Every 3 years

• Every 4 years

• Every 5 years

What is the formula to determine if a year is a leap year?

• A year divisible by 4 is a leap year

• A year divisible by 100 is a leap year

• A year divisible by 400 is a leap year

• A year divisible by 4, except for end-of-century years which must be divisible by 400