Nature of Science

Justin wanted to know if plants could grow in water alone. He placed a plant in a small pot with soil. He placed the same kind of plant in a small pot with water. Both plants were put near a sunny window. Justin watered the plant in soil each day and checked the water level of the other plant.

What factor was Justin testing in order to draw a conclusion about plant growth?

• The kinds of plants used

• The size of the container

• The place where plants were place

• The material in which the plants were grown

A student is investigating a chemical change. She slices a red apple and puts an equal amount of apple slices on each of three paper plates. She then places one paper plate inside a refrigerator, one on a table, and one near a sunny window to find out how fast the apple slices will rot in each location. She records the starting time for her investigation and the air temperature in each location.

Which of these is NOT a variable in the student's investigation?

• the kind of apple that is sliced

• where the apple slices are placed

• how long it takes the apple slices to rot

• the air temperature where the apple slices are placed

Connor thinks that building a model of an erupting volcano using baking soda and vinegar is an example of an experimental investigation. Alissa says it is not an experimental investigation.

Which student is correct and why?

• Alissa, because variables are not being controlled

• Connor, because he plans to repeat the investigation more than once

• Alissa, because models cannot be used in experimental investigations

• Connor, because other scientists have done this investigation in the past

Which question would best be answered with an experimental investigation?

• How does a seed grow into a tomato plant?

• Do tomato plants grow faster than cabbage plants?

• How does temperature affect cabbage plant growth?

• Do tomato plants have longer roots than cabbage plants?

Why is it important to do multiple trials of the same experiment?

• Multiple trials improve the reliability of the data.

• Multiple trials improve the design of the experiment.

• Multiple trials improve the methods used by the scientist.

• Multiple trials improve the predictions made by the scientist.

A scientist is testing how different substances added to water affect the rate of germination of bean seeds. He plants several beans and waters them all with different solutions.

What should his control be in his experiment?

• seed watered with saltwater

• seed watered with plain water

• seed watered with sugar water

• seed watered with vinegar water

Jan and Michael were testing the effects of the color of light on plant growth.

Which plants would be best for use as a control group?

• plants growing in the dark

• plants growing under sunlight

• plants growing under ultraviolet light

• plants growing under fluorescent light

A student is planning an experiment to find out if color affects the amount of heat an object absorbs. He will pour 500 milliliters of water from a pitcher into four clear jars of the same size. He will cover the jars in different colors of paper and set them outside in the same amount of sunlight for 2 hours, then record the change in water temperature in each jar.

How should the student create a control group in this experiment?

• Place a clear, uncovered jar with the same water in the same location and record the change in temperature.

• Place a clear jar with the same water in a shady location, cover it in white paper, and record the change in temperature.

• Place a clear, uncovered jar with the same water inside a box at the same location and record the change in temperature.

• Place a clear jar with the same water in the same location, cover it with black paper, and record the change in temperature.

A scientist conducted an investigation in order to determine the effect of pollution on the population of sea turtles in Florida. By observing the sea turtles and counting their numbers over ten years, the scientist concluded that the number of sea turtles has decreased. However, the scientist did not conduct an experiment.

Is the scientist’s conclusion still valid?

• Yes, because the scientific community no longer uses the scientific method.

• Yes, because investigations cannot always follow all steps of the scientific method.

• No, because all scientific investigations must use the same set of rules and methods.

• No, because science involves facts and this means that new and different methods are unusable.

A science class is studying how the addition of salt lowers the freezing temperature of water. They wish to find out how low the freezing temperature can go if a large amount of salt is added to water. For their first attempt to find the lowest temperature, they search the library and the Internet for information. They find the lowest temperature reported and how much salt was added; next, they successfully repeat the test as it was described and obtain the same freezing temperature. The students decide to continue the study to verify that they have found the lowest freezing temperature of water with salt added to it.

Which of the following investigations would be the most scientific approach for the students to utilize?

• Survey the students of a higher grade and average all their answers.

• Repeat the experiment from the Internet, but use sugar instead of salt.

• Ask three of the other teachers in their school and average their answers.

• Graph the results of several trials with each trial using more salt until the freezing temperature no longer changes.