A group of students is studying the effect of temperature on the density of air. They obtained the following results from a controlled experiment, and conclude that air density is directly related to temperature.   What statement best supports their conclusion?

• Lower temperatures had higher density values than higher temperatures.

• Lower temperatures had lower density values than higher temperatures.

• Higher temperatures had higher density values than lower temperatures.

• Higher temperatures did not cause any changes in density values.

Tyler is conducting an experiment in order to determine the effect that fertilizer A and fertilizer B have on the grass in his yard. He conducts multiple trials and concludes that the grass grows faster and thicker with the application of fertilizer A. How could Tyler make sure his results were valid?

• Tyler could change the amount of water each sample of grass received.

• 1. Tyler could add a third fertilizer to his experiment.

• 1. Another scientist could replicate the experiment.

• 1. Another Scientist could offer suggestions to make the experiment better.

Tania is studying the effects of acids on rocks by pouring lemon juice, vinegar, and water over pieces of chalk. Based on Tania’s procedure, shown below, why would the results from this experiment be inaccurate?

1. Place a piece of chalk that is 3 cm long in three separate beakers so that there is one piece in each beaker. 

2. Pour vinegar into one beaker, lemon juice into the second beaker, and water into the third. 

3. After 1 minute, take the chalk out. Measure and record the amount of solid chalk that remains. 

4. Repeat steps 1-3 four times.

• 1. Her procedure does not tell us how she came up with her idea for her experiment.

• 1. She should have used bigger pieces of chalk.

• 1. Her procedure is too short.

• 1. Her procedure does not list how much vinegar, lemon juice, and water should be used.

Referring to the tables below, John and Tim each conducted a controlled experiment, comparing how two surfaces absorb heat over time. After conducting the experiment with repeated trials, both John and Tim received significantly different results.  After reviewing the tables, why are John's results considered more reliable/valid?

• 1. John conducted more trials for the experiment.

• 1. Both used different materials in the experiment.

• 1. John followed the procedures more precisely.

• 1. Tim collected the data at different times during the day.

 Naomi watches birds at a bird feeder for one week and records the number of birds seen there each day. Javier places three different types of food in separate bird feeders and records the number of birds seen at each feeder every day for one week. Which student is conducting an experiment?

• 1. Naomi is conducting an experiment because she is recording data.

• 1. Naomi is conducting an experiment because her investigation has controlled variables.

• 1. Javier is conducting an experiment because his investigation has controlled variables.

• 1. Javier is conducting an experiment because he is recording data.

A group of students want to investigate erosion occurring naturally on a riverbank. The students decide to take pictures of the riverbank each day over a period of 12 months, then record what changes they see in the photos. What is the most significant limitation to this type of investigation?

• 1. Qualitative data cannot be collected from photos.

• 1. Variables, such as the weather, cannot be controlled.

• 1. The primary cause of erosion cannot be identified.

• 1. The exact amount of erosion cannot be measured.

Diana and Jane are conducting the same scientific experiment. The experiment involves dropping different colored balls and measuring the maximum height of the first bounce in centimeters. When they compare their results, they notice that their data is very different. Which of the following is the LEAST likely explanation for the discrepancy in their data?

• 1. Diana and Jane dropped the balls from different heights.

• 1. Diana and Jane used different brands of bouncy balls.

• 1. Diana and Jane dropped the bouncy balls on different surfaces.

• 1. Diana and Jane conducted their experiment at different times of the day

Why is it important for scientists to share not only their results, but also their procedure with other scientists?

• 1. Scientists don’t care about results, they only want to know the procedure.

• 1. So scientists can repeat the experiment and compare methods used, results obtained, and offer further explanations.

• 1. A scientist’s findings can only become a Law if it is repeated 10 times.

• 1. Other scientists can compare methods and then copy your data if you used the same method.

Scientific knowledge may change as new evidence or information is discovered. Which of the following would NOT be a result of new scientific research and information?

• 1. A scientific name is assigned to a recently identified plant species.

• 1. An endangered monkey species is put in a reserve for protection from extinction.

• 1. A newly discovered chemical element will be added to the periodic table of the elements.

• 1. A nonnative plant species will begin to reproduce rapidly after being introduced into a swamp ecosystem.

A scientist has been studying bullfrogs for many years. She has noticed that these bullfrogs are now laying eggs 8 days earlier than they did 20 years ago when she first began studying them. The tree trees around the pond have also grown taller and shade the water more than they did 20 years ago. What would be the best thing for the scientist to do next?

• 1. Conduct more research to see if she can determine why they are laying eggs earlier.

• 1. Choose a different species of frog to study for the next 20 years.

• 1. Conclude that the changed tree heights have affected the frogs.

• 1. Assume that the water temperature must have risen so frogs can lay eggs earlier.