Science CRT Prep Slides 1 to 20

Which graph is the best illustration of how the height of a corn plant changes as it grows?

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Answer explanation

The Y-axis represents the height of the plant and the X-axis represents the age of the plant. As a corn plant develops, it grows until it reaches maturation. The only graph that shows a steady increase in height before leveling off is Graph D.

The data table shows the number of deaths caused by influenza and pneumonia during the 1918 influenza pandemic. According to the data table, which age group shows the greatest increase in death rates caused by influenza and pneumonia from 1917 to 1918?

• <1

• 1-4

• 25-34

• 45-54

A solid cube was put into a cylinder containing four liquids with different densities as shown in the diagram. The cube descended through layer A and B, and stopped upon reaching layer C. The density of the cube most likely lies between

• 1.01 and 1.50 g/cm3.

• 1.51 and 3.50 g/cm3.  

• 3.51 and 6.00 g/cm3.

• 6.01 and 9.00 g/cm3.

Answer explanation

Density is a physical characteristic and the average density of an object is defined as the total mass per unit volume. This question does not require the students to calculate density, but they need to be able to apply the concept to a situation. Remind the students of the common example of ice in a glass of water. The ice floats because the solid state of water is less dense than the liquid state. The cylinder shows four substances A, B, C, and D with their labeled densities. If the solid cube fell through substances A and B, but stopped atop C, then it is more dense than substance B (3.50 g/cm3) and less dense than substance C (6.0 g/cm3). The correct answer is option C.

Tags

CCSS.HSG.MG.A.2

The table shows the times of moonrise and moonset in Las Vegas during December 1st-December 6th.Moonrise and Moonset Data. Based upon this data, predict the moonrise and moonset times for December 9th.

• Moonrise 12:48pm, Moonset 1:52am

• Moonrise 1:23pm, Moonset 2:52am

• Moonrise 1:38pm, Moonset 3:53am

• Moonrise 2:33pm, Moonset 4:53am

Answer explanation

The data table shows moonrise and moonset over a 6 day period with room to continue up to 9 days. By computing the trend, you see the moon rises about half an hour later each morning and sets approximately one hour later each night. Using this information, a student can predict that 3 days later, on Dec 9th, the moon will rise around 1 ½ hours later and set approximately 3 hours later than it did on Dec 6th.

Tags

CCSS.HSF.BF.A.2

Students were asked to measure a piece of string. The actual length of the string was 8.25 cm long. Which of the following shows the measurements from the most accurate group and why?

• 7.25cm, 7.75cm, 8.25cm, because these were the closest to the actual length.

• 7.2cm, 7.25cm, 7.3cm, because these had the most agreement between lengths.

• 8.25cm, 8.75cm, 9.25cm, because these had the most agreement between lengths.

• 8.2cm, 8.25cm, 8.9cm, because these were the closest to the actual length.

Answer explanation

To answer this question, you must know the scientific meaning of the term “accuracy.” Accuracy refers to the closeness of a measurement to the actual (true) value of the object being measured. Look through the answers and find which group of student-measured values are the closest to 8.25 cm. The correct answer is Option D.

Tags

CCSS.2.MD.A.3

A science class measured the total amount of rainfall at their school each month from September through May. The total rainfall data is shown in the table below.Based on the data in the table, which of these statements is an opinion?

• January is the month that had the most rainfall.

• May is the last month that rainfall data was collected.

• September is the first month of the rainfall investigation.

• April is the month that received the perfect amount of rainfall.

Answer explanation

A fact is a statement that can be proven true (or false) by comparison with some objective standard. An opinion is a subjective statement that a person believes to be true but it cannot be measured against an objective standard. The “perfect” amount of rainfall is opinion which would vary from person to person and region to region.

Use the diagram below to answer this question. The diagram shows what occurred when a can of diet soda and a can of regular soda were placed into a container of water.The can of regular soda sank to the bottom of the container, but the can of diet soda floated. Which statement best explains this observation?

• The can of regular soda is less dense than the can of diet soda.

• The can of regular soda is more dense than the can of diet soda.

• The can of regular soda has a larger volume than the can of diet soda.

• The can of regular soda has a smaller volume than the can of diet soda.

Answer explanation

Since both cans are unopened and are the same size, we know that each contains the same volume of soda. Students must draw on their knowledge that an object which floats on a liquid is less dense than the liquid, while an object which sinks through that liquid is more dense that the liquid. This lets you conclude that the composition of regular soda is higher in density than both the diet soda and the water.

Global warming is a debated subject among scientists. Some scientists support that human activities alone are dramatically warming the planet. Other scientists conclude that human activities are only partly to blame. Lastly, some scientists conclude that the Earth is warming due to natural cycles. How are different conclusions possible if all scientists are looking at the same experiments and data?

• The scientists are experts in a narrow field so they ignore the data that is outside their expertise.

• Since there can be only one right answer, one scientist has the correct answer and the rest are wrong.

• Each scientist was able to fit the data together into a logical conclusion even though the resulting models were not identical.

• Scientists pick a theory and then focus on the data that supports their theory.

Answer explanation

Evidence from the natural world is collected through observations and experimentation but it is up to the scientist to make sense of the data and draw conclusions. Therefore, two different scientists may draw two different conclusions from the same evidence. Scientific evidence is interpreted using reason and logic. However, scientific interpretation is embedded within the dogma of the time. Prior beliefs, expectations of funding agencies, and even politics may inject subtle or overt pressure to support certain “desired” conclusions.  To counter human nature, science requires that conclusions be validated by repeated experimentation which is subjected to peer review. Lastly, scientific explanations (conclusions) are well founded in logic but are tentative as scientists must be willing to modify their ideas as new evidence is uncovered.

When investigating a new cancer-fighting drug, medical researchers give some of the subjects a pill that contains the drug. Some of the other subjects are given a pill that does not contain the drug.The drug-free pill serves what purpose in the design of the investigation?

• A control

• A variable

• A separate trial

• A qualitative comparison

Answer explanation

When running an experimental investigation, researchers purposely manipulate specific variables to see what response will occur. It is important to include a control so the researchers know whether or not the same response would have occurred even without the manipulated change. If during the cancer drug study, researchers found all the subjects were beating back the cancer whether they received pills with medication or pills with no drugs, that would indicate the drug had little impact in fighting cancer. If the majority of the subjects receiving pills with the drug successfully fought the cancer while very few of the subjects receiving drug-free pills did so, that would suggest the medicine was effective.

What volume of liquid is being measured in the graduated cylinder?

• 43 mL

• 44 mL

• 45 mL

• 46 mL

Answer explanation

The correct way to read a graduated cylinder is to place it on a level surface, position yourself at eye-level to the liquid, and read the amount at the bottom of the meniscus. Before taking the reading, determine what volume is indicated per each increment in graduation (line). For the graduated cylinder in the question, going up one line represents an increase of 1 mL (some graduated cylinders will increase by increments of 0.1 mL and others increase by increments of 2 mL). In this example, a student might incorrectly select 44 mL if they do not remember to read the bottom of the meniscus. The correct answer is 43 mL.

Tags

CCSS.3.MD.A.2