Scientific Investigations
A scientist wants to determine whether water temperature affects how quickly sugar dissolves. What must the scientist change and what must be measured?
Change water temperature (IV) and measure dissolving time (DV).
A student tests whether the amount of water affects plant growth. Identify the IV, DV, and one controlled variable.
IV = amount of water; DV = plant growth; controlled = plant type, soil, sunlight, etc.
True or false: A scientific theory becomes a scientific law after enough evidence is collected.
False
A scientist watches birds in their natural habitat and records their behavior. What method is being used?
Observation
A scientist records the temperature of water every 5 minutes for one hour. What type of graph should be used?
A line graph
A student asks, “Why do plants grow?” Explain why this is not a good testable question and rewrite it to make it testable.
It is too broad and doesn't identify measurable variables.
A student tests three brands of batteries but uses a different flashlight for each brand. What is the problem with the investigation?
The flashlight is another variable that could affect the results.
A scientific law describes a pattern in nature. What does a scientific theory provide?
An explanation of how or why something happens.
The action of reproducing someone else's experiment is known as ____________
Replication
A scientist compares the average height of four different plant species.
A bar graph
Doing multiple trials of the same experiment is called __________
Repetition
Two groups of students test the effect of ramp height on car distance. Group A uses the same car for every trial. Group B uses a different car for each ramp height. Which investigation has better experimental control?
Group A
A student says, “Evolution is just a theory, so scientists aren't sure whether it happens.” What is wrong with this statement?
Scientific theories are well-supported explanations based on extensive evidence
A scientist cannot safely test the effects of a chemical on an entire ecosystem. Instead, she creates a small-scale version in a laboratory. What is this an example of?
Using a model
A scientist wants to investigate whether there is a relationship between hours of sleep and test scores for 30 students.
A scatterplot
What is the main difference between experiments and investigations?
Experiments use variables
Bart hypothesizes that root beer will produce taller hamsters if they drink it. In the experiment he's planning, what would be the dependent variable?
The height of the hamsters
A scientist observes that objects consistently accelerate toward Earth when dropped. Another scientist develops an explanation for why objects behave this way. Which scientist is primarily describing a law, and which is developing a theory?
The first is describing a law/pattern, the second is developing an explanation/theory.
Why might scientists choose to use a model instead of studying the real object or system?
The real system may be too large, small, complex, dangerous, expensive, or difficult to study
A student uses a bar graph to show how the temperature of water changes every hour for 8 hours. Would a line graph be better? Why?
Yes. A line graph is better for showing change/trends over time.
A scientist's hypothesis is not supported by the results. What should the scientist do?
Use the results as evidence, revise/reject the hypothesis, and continue investigating.
A student claims she is testing whether ramp height affects how far a car travels. She uses a different toy car for each ramp height and releases each car from a different starting position.
Name TWO variables that should have been controlled.
The toy car and starting position/release point.
Why would it be scientifically incorrect to say, “The theory of evolution will eventually become the law of evolution”?
Theories and laws serve different purposes, one does not turn into the other as evidence increases.
A scientist creates a model to predict the spread of an invasive species. The model assumes the species has unlimited food and no predators. What is the biggest concern with using this model to predict what will happen in a real ecosystem?
The model leaves out important real-world factors, so its predictions may not accurately represent what will happen.
A class surveys students about their favorite type of renewable energy. The results show the percentage of students who chose solar, wind, hydroelectric, or geothermal energy. What type of graph would be best for showing how the responses make up the whole class?
A pie chart