CHANGE, MEASURE, SAME
Which variable is the ONE factor changed on purpose?
What is the Independent variable
In a fair test, scientists should change ONE variable or MANY variables at a time?
What is One
What is data?
What is Information collected during an investigation.
What is a hypothesis?
What is A testable prediction about what will happen.
In our water investigation, what factor did we CHANGE?
What is Amount of water.
A scientist changes the amount of sunlight and measures plant height. What is the independent variable?
What is Amount of sunlight.
A student tests fertilizer. Both plants receive the same light, water, soil, and pot size. Only fertilizer changes. Fair test or flawed test?
What is Fair test.
Which is better scientific evidence: “The plant looked healthier” or “The plant grew 6 cm”?
What is “The plant grew 6 cm.”
Which is more testable: “Which plant is prettier?” or “Does the amount of water affect plant height?”
What is Does the amount of water affect plant height.
In the water investigation, what did we MEASURE?
What is Number of Seed A seeds that sprouted.
In that same experiment, what is the dependent variable, and name one possible constant.
DV = plant height. Constant could be water, soil, plant type, pot size, etc.
A student tests fertilizer. Plant A gets fertilizer and 100 mL of water. Plant B gets no fertilizer and 50 mL of water. Fair or flawed? Explain.
What is Flawed. Fertilizer and water both changed.
Tray A had 18 sprouts. Tray B had 6 sprouts. Which tray had greater germination, and what evidence supports your answer?
What is Tray A; 18 sprouts compared with 6.
In the question “How does the amount of light affect plant growth?”, what is being changed and what is being measured?
What is Change = amount of light; Measure = plant growth.
In the light investigation, name the independent variable, dependent variable, and one constant.
What is IV = amount of light; DV = number of sprouts; constant = water, heat, or seed type.
A scientist changes water, light, and fertilizer but only measures plant height. Why can the scientist not tell what caused the result?
What is Too many independent variables changed at the same time.
How could the student in the previous experiment fix the investigation?
What is Keep the water amount the same and change only fertilizer.
A student's hypothesis was not supported by the data. Did the experiment fail? Explain.
What is No. The data still provide evidence and help scientists learn about the question.
Why is “Which paper towel is the best?” a weak scientific question?
What is “Best” is unclear/opinion-based and does not identify a measurable result.
During the 100% Germination Challenge, you could change water, light, and heat at the same time. Why couldn't those results tell you which ONE factor caused a difference in sprouting?
What is Because multiple variables changed, so the cause could not be isolated.
Design a fair test of whether temperature affects seed germination. Give the CHANGE, MEASURE, and at least three SAMEs.
What is CHANGE = temperature; MEASURE = number/percent germinated; SAME = seed type, water, light, number of seeds, time, etc.
A student uses one plant with fertilizer and one plant without fertilizer, then concludes fertilizer causes faster growth. Give two weaknesses in the evidence and explain how to improve the investigation.
What is Too few plants/trials; individual differences could affect results. Use multiple plants/repeated trials while keeping conditions controlled.
Group A gets 18 sprouts, but another group using the same settings gets only 9. Give two possible scientific reasons for the different results and one way to improve confidence in the evidence.
What is Possible uncontrolled variables, procedure differences, measurement error, chance; repeat trials/use more samples/standardize procedures.
Rewrite “Which paper towel is the best?” as a testable scientific question and identify the CHANGE and MEASURE.
What is Example: “How does paper towel brand affect the amount of water absorbed?” CHANGE = brand; MEASURE = amount of water absorbed.
You are asked to test heat next in the Gizmo. Describe a three-tray experiment that would allow you to determine whether heat affects germination. Explain why your design is fair.
What is Use different heat levels in the trays while keeping seed type, water, light, number of seeds, and time the same; measure sprouts. It is fair because only heat changes.