Scientific Method & Variables
A testable prediction written as "If ___, then ___, because ___" is called a
Hypothesis
What tool measures temperature?
Thermometer
What do scientists call the data collected directly from an experiment before any calculations?
Raw data
Why should long hair be tied back in the lab?
To prevent it from catching fire or getting into chemicals
You notice your ice cream melts faster on a sunny day. This is an example of an observation or an inference?
Observation
The variable that you change on purpose:
Independent variable
This term describes how close a measured value is to the true value.
Accuracy
What are two essential elements that must be included on a graph’s axes labels?
The variable name (e.g., time, distance, temperature) and the units of measurement (e.g., seconds, meters, °C)
Why should you avoid mixing unknown chemicals in a laboratory?
Mixing unknown chemicals can lead to hazardous reactions, such as the production of toxic gases, fires, or explosions.
A student notices that her plant’s leaves are turning yellow. She thinks it might be due to too much water. Is this an observation or an inference?
Inference
In an experiment, why is it important to do multiple trials for the same test?
To ensure results are reliable and not due to chance
What measurement instrument would you use to measure the diameter of a needle accurately?
Vernier caliper
You collected 3 trials of plant growth: 50 cm, 52 cm, 48 cm. What is the average?
50 cm
What should you do first if you accidentally spill acid on a laboratory table?
Inform the teacher immediately.
What instrument, SI unit, and symbol would you use to measure the temperature of boiling water?
Instrument:
Thermometer
SI Unit:
Kelvin
Symbol:
K
You are a botanist designing an experiment to investigate how the amount of sunlight exposure impacts the growth of plants. In your experiment, what would be the independent variable, the dependent variable, and one controlled variable?
Independent variable: hours of sunlight exposure Dependent variable: plant growth measured in cm Controlled variable: amount of water provided, type of soil, humidity
You need to measure 78.6 mL of water accurately. Which tool is most appropriate and why? 100ml beaker or 100ml graduated cylinder?
100 mL graduated cylinder, because it has more markings compared to a beaker and minimizes guessing.
What is one reason why scientists convert processed data tables into graphs instead of just keeping the tables?
To identify patterns
To compare results
To communicate findings clearly
Why is it unsafe for students to taste or smell unknown chemicals in a laboratory?
The chemical can be toxic, corrosive, or harmful in some way.
You want to find out how much mass of sugar dissolves in 100 mL of water at 25°C. What measurements should you take and what instruments would you use?
Mass - balance
Volume - Graduated cylinder
Temperature - Thermometer
You are a researcher designing an experiment to investigate how music impacts focus levels in students studying. How would you vary the independent variable, and how would you measure the dependent variable?
Independent variable variation:
Expose students to different types of music (e.g., classical, pop, no music) during study sessions.
Have students study with and without listening to music.
Dependent variable measurement:
Number of correct answers on a test
Mention three things you can do to take an accurate measurement of a pencil's length using a ruler.
Align the Zero Mark (not the edge of the ruler itself) to one end of the pencil
Ensure the ruler is parallel to the length of the pencil.
Position your eye directly above the mark you are reading on the ruler.
If the end of the pencil falls between the smallest marks on the ruler, estimate the final digit (or fraction) carefully.
A scientist is studying how the amount of fertilizer (in grams) affects the height of a plant (in centimeters) in one month. When graphing the results, which variable should be placed on the x-axis, and why?
The amount of fertilizer (in grams) should be placed on the x-axis (horizontal axis). This is because the x-axis always represents the independent variable. The independent variable is the factor that is intentionally changed (the cause), which in this case is the amount of fertilizer.
What are two safety precautions to take before conducting a vinegar and baking soda experiment in a laboratory?
How can you find the density of a ring made of an unknown material using water, a graduated cylinder, a digital balance, paper, and a pencil?
Measure mass
Place the ring on the digital balance.
Record the mass (g) on your paper.
Measure water volume (before)
Pour some water into the graduated cylinder.
Record the starting water level (mL).
Measure water volume (after)
Carefully drop the ring into the water.
Record the new water level (mL).
Find volume of ring
Subtract: final volume − initial volume.
Result = volume of ring (mL or cm³).
Calculate density
Use the formula:
Density = Mass ÷ Volume