Think Like a Scientist
Information gathered using our senses or scientific tools is called this.
What is an observation?
An observation is information you directly notice or measure. Seeing that a leaf is green or measuring its length are observations. An inference goes further by explaining what you think an observation means.
This is the variable a scientist purposely changes. Give either of its two names.
What is the independent variable, also called the manipulated variable?
The scientist chooses which factor to change. For example, when testing how water temperature affects dissolving time, water temperature is the independent variable.
Name a tool used to measure mass and a unit used to record it.
What is a balance, with mass recorded in grams or kilograms?
Mass measures the amount of matter in an object. A balance measures mass. Grams are useful for smaller objects, while kilograms are useful for larger masses.
Identify the word that means “spin” and the word that means “orbit.”
What are rotate for “spin” and revolve for “orbit”?
Rotation means turning around an axis. Revolution means traveling around another object. Earth rotates on its axis while revolving around the Sun.
This force keeps Earth in orbit around the Sun.
What is gravity?
Gravity attracts objects with mass toward each other. The Sun’s gravity continually pulls Earth toward it. Combined with Earth’s forward motion, this keeps Earth traveling in an orbit.
This is a possible, testable answer to a scientific question.
What is a hypothesis?
A hypothesis predicts what you think will happen. Scientists test it by collecting evidence. For example: “If water temperature increases, then sugar will dissolve faster.”
A student tests how water temperature affects the time sugar takes to dissolve. Identify the independent and dependent variables.
What are water temperature as the independent variable and dissolving time as the dependent variable?
Water temperature is purposely changed. The time sugar takes to dissolve is measured to see how it responds. The dependent variable is also called the responding variable.
This is the number of millimeters in 7 centimeters.
What is 70 millimeters?
There are 10 millimeters in every centimeter. Multiply 7 by 10 to get 70. The length stays the same even though the number changes because millimeters are smaller units.
These are the approximate times Earth takes to complete one rotation and one revolution around the Sun.
What are 24 hours for one rotation and 365 days for one revolution?
One full rotation takes about one day. One full revolution around the Sun takes about one year. These are two different motions happening at the same time.
This term means half of a sphere.
What is a hemisphere?
Earth can be divided into hemispheres. The equator divides it into the Northern and Southern Hemispheres. Each hemisphere is half of Earth.
Which question is testable, and why?
A. Which paper towel brand is the best?
B. How does paper towel brand affect the amount of water it absorbs?
What is B, because it identifies something to change and something to measure?
The scientist changes the paper towel brand and measures the amount of water absorbed. “Best” is unclear because it could mean strongest, cheapest, or most absorbent.
A student compares plant growth with and without fertilizer. Identify the control group and explain its purpose.
What are the plants without fertilizer, which provide a comparison?
The control group does not receive the fertilizer treatment. Comparing it with the fertilized plants helps the scientist determine whether fertilizer affects growth. Other growing conditions should stay the same.
How should you read the water level in a graduated cylinder?
A. Hold it in your hand and look down at the water.
B. Place it on a level surface and read the bottom of the meniscus at eye level.
C. Place it on a level surface and read the top of the meniscus from above.
D. Tilt it toward you and read the water level.
What is B?
The meniscus is the curved surface of the water. Read its lowest point at eye level while the cylinder rests on a level surface. Looking from above or below can make the measurement appear higher or lower than it actually is.
This Earth motion causes day and night. Explain which side experiences each.
What is rotation, with daytime on the side facing the Sun and nighttime on the side facing away?
The Sun lights approximately half of Earth at a time. As Earth rotates, locations move into and out of sunlight. Earth’s revolution around the Sun does not cause the daily cycle of day and night.
A student says, “The Sun goes around Earth every day because I see it move across the sky.” Identify the motion that actually explains this observation.
What is Earth’s rotation on its axis?
The Sun appears to move because our position on the rotating Earth changes. Seeing something move across the sky does not necessarily mean it is traveling around Earth. Earth also revolves around the Sun over approximately one year.
Scientists repeat an experiment several times instead of testing only once. Why?
What is to make the results more reliable?
One trial could give an unusual result because of a mistake or chance. Repeating the experiment helps scientists check whether they get similar results each time.
A student tests how ramp height affects the distance a toy car travels. Name three things that should stay the same.
What are the toy car, ramp surface, and release method?
These are constants, also called controlled or standardizing variables. Keeping them the same helps isolate the effect of ramp height. Other acceptable examples include the floor surface and measuring method.
A rectangular block is 6 cm long, 3 cm wide, and 2 cm tall. Calculate its volume.
What is 36 cubic centimeters?
For a rectangular solid, volume equals length × width × height. Multiply 6 × 3 × 2 to get 36 cm³. Cubic centimeters describe how much space the block occupies.
Define Earth’s axis and identify its approximate tilt.
What is an imaginary line through Earth’s center that Earth rotates around, tilted about 23.5 degrees?
The axis passes through the North and South Poles. Earth spins around this imaginary line. Its axis is tilted about 23.5 degrees from a line perpendicular to its orbital plane.
About how many complete trips around the Sun has a person made by the time they are 12 years old?
Earth completes one revolution around the Sun each year. By their 12th birthday, a person has traveled around the Sun approximately 12 times.
A student asks, “How does the amount of sunlight affect plant growth?” Write a hypothesis using “If…then…”
What is “If a plant receives more sunlight, then it will grow taller”?
A hypothesis is a prediction that can be tested. This prediction connects the amount of sunlight to plant growth. Accept other reasonable, testable predictions, including predicting less growth or no change.
Plant A gets fertilizer, extra water, and sunlight. Plant B gets no fertilizer, less water, and shade. Explain why this is not a fair test of fertilizer and how to fix it.
What is changing several factors at once, which should be fixed by changing only the fertilizer treatment?
The plants could grow differently because of fertilizer, water, or light. To test fertilizer fairly, keep the amount of water, sunlight, plant type, soil, and growing time the same. Then compare growth with and without fertilizer.
A rock raises the water level from 40 mL to 57 mL. Find its volume in mL and cm³. Another group repeatedly measures the rock as 12 mL. If 17 mL is the accepted volume, describe that group’s accuracy and precision.
What is a volume of 17 mL, or 17 cm³, with the other group’s results being precise but inaccurate?
Subtract the starting water level from the final level: 57 − 40 = 17 mL. Because 1 mL equals 1 cm³, the rock occupies 17 cm³. The other group’s measurements agree with each other, making them precise, but differ from the accepted value, making them inaccurate.
Identify the Earth motion that explains the Sun’s apparent daily movement across the sky and the motion that helps explain different nighttime constellations during different seasons.
What are rotation for the Sun’s apparent daily movement and revolution for changing seasonal constellations?
Earth’s rotation makes the Sun appear to travel from east to west each day. As Earth revolves around the Sun, the nighttime side faces different directions in space. This allows us to see different constellations throughout the year.
Which statement correctly describes a solar eclipse?
A. The Moon moves between the Sun and Earth, blocking sunlight from reaching part of Earth.
B. Earth moves between the Sun and Moon, casting its shadow on the Moon.
What is A?
A solar eclipse happens when the Moon blocks our view of the Sun. Option B describes a lunar eclipse, when Earth’s shadow falls on the Moon.