A student tests whether water temperature changes how fast sugar dissolves. She uses 10 g of sugar each time in water at 20°C, 40°C, and 60°C. What is the independent variable?

A class changes ramp height to test how far a toy car rolls after leaving the ramp. What outcome is the dependent variable?

Students test how light color affects plant growth. They use the same seed type, soil, pot size, and water amount. Which named variable is controlled?

A student compares two paper towels. Towel A gets 50 mL of water, and Towel B gets 100 mL. What change would make the test fair?

A student tests whether fertilizer amount affects bean plant height. She gives pots 0 g, 5 g, or 10 g of fertilizer and keeps watering the same. What is changed on purpose?

A group investigates whether salt amount affects the freezing point of water. They measure the temperature when each sample freezes. What is the dependent variable?

A class tests how soil type affects drainage. Every cup gets 200 mL of soil, 50 mL of water, and the same cup size. Which variable is controlled?

A student tests two laundry detergents. Detergent A is used in 20°C water, and Detergent B is used in 40°C water. What should change for a fair comparison?

A lab group tests how surface texture affects sliding friction. They pull the same wooden block across carpet, sandpaper, and tile. What is the independent variable?

Students test how exercise time affects pulse rate. They jog for 0, 2, or 4 minutes and then count heartbeats. What is the dependent variable?

Students compare how ball mass affects rolling speed down a ramp. They use the same ramp angle, release point, and distance. What is a controlled variable?

A class tests which cup keeps water warm longest. Cup A starts with 80°C water, but Cup B starts with 60°C water. What change makes the test fair?

A student investigates how blade length affects a paper helicopter's fall time. She makes helicopters with 4 cm, 6 cm, and 8 cm blades. What is the independent variable?

A teacher tests how beak shape affects the number of beans picked up in 30 seconds. Students record beans collected with each tool. What is the dependent variable?

Students test whether container color affects how quickly ice melts. They use identical ice cubes, the same lamp distance, and equal room temperature. What is controlled?

A student compares seed germination in two soils. One tray receives 20 mL of water daily, and the other receives 40 mL. What should be changed?

A group studies how magnet distance affects the number of paper clips picked up. They place the magnet 1 cm, 3 cm, and 5 cm away. What variable is changed?

A class tests whether music volume affects how many math problems students finish in 5 minutes. What is the dependent variable?

Students test how baking soda amount affects balloon size when mixed with vinegar. They use the same bottle, vinegar volume, and balloon type. Which is controlled?

A student times two toy cars on a track. Car A starts from a 5 cm height, and Car B starts from a 15 cm height. What change improves fairness?

A class tests whether water pH affects duckweed growth. Tanks have pH 5, pH 7, and pH 9 water with the same light. What is the independent variable?

A student changes the length of a pendulum string and records the time for 10 swings. What is the dependent variable?

Students test how vinegar concentration affects eggshell mass after soaking. They keep the soaking time, eggshell size, and liquid volume the same. What is controlled?

A group compares sponge absorbency. Sponge A is squeezed before measuring, but Sponge B is not squeezed. What should happen to make the test fair?

Students test how sunlight time affects algae growth. Bottles receive 2, 6, or 10 hours of light each day. What is the independent variable?

A group investigates how salt concentration affects brine shrimp hatching. After two days, they count hatched shrimp. What is the dependent variable?

A class tests how air temperature affects cricket chirps. They observe crickets for the same 1-minute time, in the same container, with the same food. Which variable is controlled?

A student tests glue strength on wood and plastic. The wood sample dries for 24 hours, but the plastic sample dries for 2 hours. What change is needed?

A student tests how wire length affects bulb brightness in a circuit. Circuits use 10 cm, 20 cm, and 30 cm wires with the same battery. What is manipulated?

Students test whether parachute surface area affects drop time. They drop each parachute from 2 m and time its fall. What is the dependent variable?

A group tests how mouthwash type affects bacteria growth on agar plates. They use the same swab method, agar type, and incubation temperature. Which is controlled?

A class compares how fast three tablets dissolve. Tablet A uses 100 mL water, Tablet B uses 150 mL, and Tablet C uses 200 mL. What should be changed?

Students soak identical steel wool pads in different liquids, such as water, salt water, and vinegar. After 3 days, they check how much rust formed on each pad. What is the independent variable?

A student wraps identical cups of hot water in 1, 2, or 3 layers of foam and reads the thermometer in each cup 30 minutes later. What is the dependent variable?

A class places dishes of water in front of a fan set to low, medium, and high. They measure how much water evaporates from each dish in 1 hour. Which variable should be controlled?

A student compares how two soils support worms. Soil A is kept moist, while Soil B is kept dry. What change would make the comparison fair?

A group mixes batches of dough with 2 g, 5 g, and 8 g of yeast and measures how high each batch rises in 1 hour. What is the independent variable?

Students sprinkle table salt, rock salt, or Epsom salt on identical ice cubes. After 10 minutes, they weigh the ice that has not melted. What is the dependent variable?

A student fills glass, plastic, and metal cups with a cold drink and weighs the water droplets that form on the outside of each cup after 10 minutes. Which variable should be controlled?

A class tests whether music type affects plant growth. Plant A hears rock music for 4 hours daily, but Plant B hears classical music for 8 hours daily. What change makes it fair?