WCAS - Washington Comprehensive Assessment of Science Science and Engineering Practices Questions and Answers

Question 1

A student builds a model of the solar system using foam balls of different sizes and places them at varying distances from a central lamp representing the Sun.
What is the primary scientific purpose of this type of model?

Accepted Answer

To help visualize and understand the relative sizes and positions of celestial bodies.

Answer

To prove that the Sun is the center of the solar system.

Answer

To perfectly replicate every detail of the solar system.

Answer

To calculate the exact gravitational forces between the planets.

Question 2

A student wants to investigate how the color of light affects the growth rate of bean plants. She places three identical bean plants in separate containers with the same type of soil and gives them the same amount of water. One plant is exposed to red light, one to green light, and one to white light for 12 hours a day. She measures the height of each plant every day for two weeks. What is the independent variable in this investigation?

Accepted Answer

The color of the light.

Answer

The height of the bean plants.

Answer

The amount of water given to each plant.

Answer

The type of soil used.

Question 3

A group of students collected the following data to determine the effect of water temperature on the time it takes for 5 grams of salt to dissolve completely.

| Water Temperature (°C) | Time to Dissolve (seconds) |
| :--- | :--- |
| 20 | 125 |
| 40 | 80 |
| 60 | 45 |
| 80 | 20 |

Based on the data in the table, which conclusion is best supported?

Accepted Answer

As the water temperature increases, the time it takes for salt to dissolve decreases.

Answer

The rate of dissolving is unrelated to the water temperature.

Answer

As the water temperature decreases, the time it takes for salt to dissolve decreases.

Answer

Salt dissolves fastest in the coldest water.

Question 4

A student claims, "Plants require sunlight to grow." Which of the following statements provides the strongest scientific evidence to support this claim?

Accepted Answer

An experiment was conducted where one plant was placed in sunlight and an identical plant was placed in a dark room; the plant in the sun grew 5 cm while the plant in the dark did not grow.

Answer

My friend told me that her plant died when she kept it in a dark closet.

Answer

It is a well-known fact that all plants need sunlight.

Answer

Plants look healthier and greener when they are outside in the sun.

Question 5

A student is curious about rainfall in their city. Which of the following is a scientifically testable question that the student could investigate for a school project?

Accepted Answer

Does the amount of rainfall affect the growth of grass on the school lawn?

Answer

Is rain good or bad for the city?

Answer

Why does it feel so sad when it rains?

Answer

What is the most beautiful cloud formation that produces rain?

Question 6

A student observes that the grass is wet on a cool, clear morning, even though it did not rain. Which of the following statements best represents a scientific explanation for this observation, rather than just another observation?

Accepted Answer

The air cooled overnight, causing invisible water vapor in the air to condense into liquid water on the cool blades of grass.

Answer

The grass is wet, and so is the top of my mailbox.

Answer

The water on the grass will probably evaporate when the sun comes out.

Answer

The sprinkler system must have turned on by accident during the night.