Scientific Method and Density Quick-Check

A student hypothesizes that water from infrequently used school faucets contains more chemical impurities than the water from frequently used faucets. At the same time of day, the student uses a water test kit to measure the water impurities from the different faucets. Which is the manipulated variable in this investigation?

• The chemicals used to test the water
• The amount of water per sample
• The time of day when water is collected
• The locations of water collection

In an experiment, what is the factor being tested or changed on purpose?

• Dependent Variable

• Independent Variable

• Constant

• Experimental Error

What is the dependent variable?

• Amount of each trash
• Type of trash
• Where the trash is located
• When the trash was picked up

What is the independent variable?

• Type of Water

• Type of Plant

• Plant Growth

• Number of Days

What is the experimental group?

Testing a hypothesis often involves a(n):

• answer
• experiment
• problem
• safety check

An experiment is performed on plants to see how different liquids affect plant growth. Each plant in the experiment is given a different liquid; water, apple juice, or milk. Each plant has the same amount of soil, sunlight, and listens to the same music. In this investigation, what are the constants?

• Type of plant, amount of music, and sunlight

• Water, apple juice, milk

• Plant growth

Students made a hydrometer by sealing the end of a straw with wax and adding some sand until the hydrometer barely floated in fresh water. The diagram shows what the students observed when they used the hydrometer to test water from three different sites. Each water sample had the same temperature. Which of these explanations best fits these observations?

• Estuaries are less salty than fresh water.
• Oceans support more microbes than fresh water.
• Salt water is denser than fresh water.
• Ocean water can freeze at lower temperatures than fresh water.

A student conducted the experiment shown. She slowly poured the blue colored cold water and red colored hot water at the same time into a tank of room temperature water. What will most likely happen immediately after the hot and cold water are added to the tank?

• The blue and red water will instantly mix together forming a purple color

• The blue and red water will mix together, but remain separate from the room temp water

• The blue water will sink to the bottom and the red will rise to the top of the tank

• The red water will sink to the bottom and the blue will rise to the top if the tank

A student measured the mass and volume of a cube. What is the density of the cube.

• 0.35 g/cm³

• 1.36 g.cm³

• 0.79 g/cm³

• 1.02 g/cm³