Scientific Method

In an appropriately designed experiment, a scientist is able to test the effect of

• a single variable

• multiple variables

• the hypothesis

• scientific observations

In order to be accepted, a scientific theory must be

• widely tested and supported by extensive data

• based on the results of a single experiment

• controversial and cause debate

• in line with all previous historical ideas

Which statement about a controlled experiment is true?

• All variables must be kept the same.

• Controlled experiments cannot be performed on living things.

• Scientists always use controlled experiments.

• Only one variable is changed at a time.

Which statement more accurately describes scientific inquiry?

• It ignores information from other sources.

• It does not allow scientists to judge the reliability of their sources.

• It should never be involve ethical decisions about the application of scientific knowledge.

• It may lead to explanations that combine data with what people already know about their surroundings

The development of an experimental research plan should not include a

• list of safety precautions for the experiment

• list of equipment needed for conducting the experiment

• procedure for the use of technologies needed for the experiment

• conclusion based on data expected to be collected in the experiment

An experiment was carried out to answer the question “Does the pH of water affect the growth of radish plants?” Two groups of ten radish plants were set up. One group was watered with water having a pH of 3.0, and the other group was watered with water having a pH of 7.0. Both groups of plants received the same amount and intensity of light, the same amount of water, and they were grown in the same type of soil. The heights of the radish plants were measured every 2 days for a period of 2 weeks.

Which sentence is a possible hypothesis that was tested in this experiment?

• Does the pH of water affect the growth of radish plants?

• Will the amount of water alter the heights of the radish plants?

• The temperature of the water will affect the heights of the radish plants.

• The pH of the water will affect the heights of the radish plants.

An experiment was carried out to answer the question “Does the pH of water affect the growth of radish plants?” Two groups of ten radish plants were set up. One group was watered with water having a pH of 3.0, and the other group was watered with water having a pH of 7.0. Both groups of plants received the same amount and intensity of light, the same amount of water, and they were grown in the same type of soil. The heights of the radish plants were measured every 2 days for a period of 2 weeks.

What was the dependent variable in this experiment?

• heights of the plants

• pH of the water

• temperature of the soil

• type of soil

An experiment was carried out to answer the question “Does the pH of water affect the growth of radish plants?” Two groups of ten radish plants were set up. One group was watered with water having a pH of 3.0, and the other group was watered with water having a pH of 7.0. Both groups of plants received the same amount and intensity of light, the same amount of water, and they were grown in the same type of soil. The heights of the radish plants were measured every 2 days for a period of 2 weeks.

Which activity might help to increase the validity of this experiment?

• repeating the experiment several times

• using two different types of radish seeds in each group

• using the same pH for both groups of plants

• placing one set of plants in the sunlight and one in darkness

A possible explanation to a problem that has not yet been tested. 

• data
• theory
• hypothesis
• fact

This part of the experiment serves as a basis of comparison; the one variable being tested has been omitted. 

• experimental group
• control group
• data
• variables