1. A scientist investigates how the amount of sunlight affects the growth rate of tomato plants.
The plants are exposed to different hours of sunlight daily, while all other conditions, such as
watering schedule and soil type, are kept the same.
2. A group of researchers studies the effect of temperature on the speed at which sugar dissolves
in water. They use water at 20°C, 40°C, and 60°C while stirring each sample at the same speed.
3. Students measure how the type of insulation affects the time it takes for a hot drink to cool.
They test cups wrapped in foam, aluminum foil, and cloth, ensuring that the starting temperature
of the drink is the same in each case.
4. An experiment tests whether different fertilizers affect the yield of corn crops. One field
receives organic fertilizer, another receives chemical fertilizer, and a third is left unfertilized. The
fields are of equal size and receive the same amount of water.
5. A researcher observes how varying the amount of caffeine in coffee influences students’ test
performance. Participants are given coffee with different caffeine levels and are then asked to
complete the same set of math problems.
6. Engineers evaluate the effect of bridge material on its ability to hold weight. They construct
bridges from steel, wood, and concrete and test the maximum weight each can hold under
controlled weather conditions.
7. A study examines how water pH levels influence the survival rate of freshwater fish. The fish
are placed in tanks with different pH levels, while the water temperature and feeding schedules
are kept constant.
8. A biologist wants to determine if the size of bird feeders affects the number of birds visiting
them. She places small, medium, and large feeders in similar locations and monitors the number
of visits over a week.
9. A chemist studies how salt concentration affects the freezing point of water. Solutions with
different salt concentrations are prepared and cooled in identical freezers.
10. Researchers test whether the frequency of watering affects the height of sunflower plants.
One group is watered daily, another every three days, and a third once a week. All plants are
grown in identical pots with the same type of soil.
11. A team of environmental scientists examines how the presence of pollutants impacts the
oxygen levels in a lake. They measure oxygen levels at different parts of the lake, considering
areas near and far from industrial discharge points.
12. Students investigate how the type of exercise (e.g., running, swimming, cycling) affects heart
rate. Participants perform each activity for 10 minutes, and their heart rates are measured
immediately afterward.
13. A farmer tests how planting density affects crop yield. He plants seeds at three densities
(low, medium, high) and records the total yield at harvest. The same type of seed and fertilizer is
used for all plots.
14. A researcher examines how the type of fabric (cotton, polyester, or wool) affects the time it
takes for water to evaporate. Identical amounts of water are placed on each fabric type and
exposed to sunlight.
15. Scientists study how noise levels in the environment affect the growth of laboratory rats. The
rats are placed in enclosures with varying levels of noise exposure (low, moderate, high), and
their weight gain is recorded over a month.
Instructions for Students:
For each scenario:
1. Identify the Independent Variable (IV).
2. Identify the Dependent Variable (DV).
3. List the Controlled Variables (CV).
4. Name at least one potential Extraneous Variable (EV).
1.
IV: Amount of sunlight (hours per day)
DV: Growth rate of tomato plants
CV: Watering schedule, soil type, plant species
EV: Weather changes, pests, temperature fluctuations
2.
IV: Temperature of the water
DV: Time for sugar to dissolve
CV: Amount of water, amount of sugar, stirring speed
EV: Air pressure, purity of sugar or water
3.
IV: Type of insulation (foam, aluminum foil, cloth)
DV: Time for the hot drink to cool
CV: Starting temperature of the drink, cup size, room temperature
EV: Airflow in the room, material of the cup
4.
IV: Type of fertilizer (organic, chemical, none)
DV: Corn crop yield
CV: Field size, water amount, sunlight, crop variety
EV: Pest infestation, weather conditions
5.
IV: Caffeine level in coffee
DV: Test performance (e.g., accuracy or completion time)
CV: Test difficulty, duration of the test, participants’ prior knowledge
EV: Students’ stress levels, sleep quality before the test
6.
IV: Bridge material (steel, wood, concrete)
DV: Maximum weight the bridge can hold
CV: Bridge design, weather conditions, construction method
EV: Quality of materials, human error in testing
7.
IV: Water pH levels
DV: Survival rate of freshwater fish
CV: Water temperature, feeding schedule, species of fish
EV: Tank cleanliness, oxygenation levels in the water
8.
IV: Size of bird feeders (small, medium, large)
DV: Number of birds visiting the feeders
CV: Location of feeders, type of birdseed, observation duration
EV: Presence of predators, weather conditions
9.
IV: Salt concentration in the water
DV: Freezing point of water
CV: Volume of water, cooling method, type of salt
EV: Impurities in the water, freezer efficiency
10.
IV: Frequency of watering (daily, every 3 days, once a week)
DV: Height of sunflower plants
CV: Pot size, soil type, sunlight exposure, plant type
EV: Fertility of soil, unexpected weather conditions
11.
IV: Proximity to industrial discharge points
DV: Oxygen levels in the lake
CV: Measurement tools, time of day measurements are taken
EV: Temperature of the water, presence of aquatic plants
12.
IV: Type of exercise (running, swimming, cycling)
DV: Heart rate after 10 minutes of exercise
CV: Duration of exercise, participants' fitness levels
EV: Room temperature, hydration level of participants
13.
IV: Planting density (low, medium, high)
DV: Crop yield (total harvested produce)
CV: Type of seed, fertilizer used, watering schedule
EV: Soil quality, pest control measures
14.
IV: Type of fabric (cotton, polyester, wool)
DV: Time for water to evaporate
CV: Amount of water, sunlight exposure, room temperature
EV: Humidity levels, thickness of fabric samples
15.
IV: Noise levels (low, moderate, high)
DV: Weight gain of laboratory rats
CV: Feeding schedule, enclosure size, rat breed
EV: Health conditions of rats, quality of feed
