0.2 A3, A4, A6, B4, B6: Accuracy, Precision, And Units

1. A student observes a garden plot. Several plants shaded by a tree are not as large as those of the same species growing in the full sun. The student asks, "Why are the plants growing in the shade smaller than the plants growing in the sun?" Which is the most reasonable hypothesis to explain the student's observations?

The tree removes water from the soil. The drier soil limits the growth of those plants growing near the tree.

The tree removes minerals from the soil. The mineral-reduced soil limits the growth of those plants growing near the tree.

Answer option 4

The most reasonable hypothesis to explain the student's observations is that the tree blocks sunlight, lowering the light level in the shaded area. This limits the growth of this plant species, which grows best in direct sunlight. This explanation is supported by the fact that the plants growing in the shade are not as large as those growing in the full sun, indicating that light availability plays a crucial role in their growth. The other options of the tree removing water or minerals from the soil do not directly address the difference in size between the shaded and sunlit plants.

Explanation

The most reasonable hypothesis to explain the student's observations is that the tree blocks sunlight, lowering the light level in the shaded area. This limits the growth of this plant species, which grows best in direct sunlight. This explanation is supported by the fact that the plants growing in the shade are not as large as those growing in the full sun, indicating that light availability plays a crucial role in their growth. The other options of the tree removing water or minerals from the soil do not directly address the difference in size between the shaded and sunlit plants.

2. A student needs to collect quantitative data about the pendulum lab. Which of the following is NOT considered quantitative data?

Length of string

Initial dropping height

Period of the swing

Material used to change mass

Quantitative data refers to numerical measurements or values that can be measured or counted. In this context, the length of the string, initial dropping height, and period of the swing can all be quantitatively measured or expressed in numerical values. However, the material used to change mass is not a numerical measurement but rather a qualitative characteristic. Therefore, it is not considered quantitative data.

Explanation

Quantitative data refers to numerical measurements or values that can be measured or counted. In this context, the length of the string, initial dropping height, and period of the swing can all be quantitatively measured or expressed in numerical values. However, the material used to change mass is not a numerical measurement but rather a qualitative characteristic. Therefore, it is not considered quantitative data.

3. In our pendulum lab our hypotheses could have arisen from....

Observations

Prior Knowledge

Inferences

All of the above

The correct answer is "All of the above" because in the pendulum lab, hypotheses could have arisen from observations, prior knowledge, or inferences. Observations of the pendulum's behavior, such as its swinging motion, could lead to the formation of hypotheses. Prior knowledge about pendulums and their properties could also contribute to the development of hypotheses. Additionally, inferences based on the observed data and prior knowledge could be used to generate hypotheses. Therefore, all three options - observations, prior knowledge, and inferences - could have played a role in forming the hypotheses in the pendulum lab.

Explanation

The correct answer is "All of the above" because in the pendulum lab, hypotheses could have arisen from observations, prior knowledge, or inferences. Observations of the pendulum's behavior, such as its swinging motion, could lead to the formation of hypotheses. Prior knowledge about pendulums and their properties could also contribute to the development of hypotheses. Additionally, inferences based on the observed data and prior knowledge could be used to generate hypotheses. Therefore, all three options - observations, prior knowledge, and inferences - could have played a role in forming the hypotheses in the pendulum lab.

4.

The chart shows the density of seawater samples collected from the Gulf of Mexico by four different groups. Which group's data are most precise?

Group 1

Group 2

Group 3

Group 4

Could calculate and find an overall difference for group 2 per trial compared to average is about 0.001

Explanation

Could calculate and find an overall difference for group 2 per trial compared to average is about 0.001

5. Which of the following will allow measurement of a liquid's volume with the greatest precision?

50 mL cylinder graduated in 1 mL increments

100 mL cylinder graduated in 0.5 mL increments

100 mL cylinder graduated in 1 mL increments

200 mL cylinder graduated in 5 mL increments

Precision = small increments

Explanation

Precision = small increments

6. A student performed an analysis of a sample for its calcium content and got the following results: 14.92% 14.91% 14.88% 14.91% The actual amount of calcium in the sample is 14.90%. What conclusions can you draw about the accuracy and precision of these results?

While precise, these results are not accurate.

While accurate, these results are not accurate.

These results are both accurate and precise.

These results are neither accurate nor precise.

The student's results are both accurate and precise because they are consistently close to the actual amount of calcium in the sample (14.90%). Accuracy refers to how close a measurement is to the true or accepted value, while precision refers to how close multiple measurements are to each other. In this case, the results are consistently close to the actual value, indicating precision, and they are also close to the actual value, indicating accuracy.

Explanation

The student's results are both accurate and precise because they are consistently close to the actual amount of calcium in the sample (14.90%). Accuracy refers to how close a measurement is to the true or accepted value, while precision refers to how close multiple measurements are to each other. In this case, the results are consistently close to the actual value, indicating precision, and they are also close to the actual value, indicating accuracy.

7. Which tool below is most precise?

Trial	Volume Shown by Graduated Cylinder	Volume Shown by the Buret
1	25 mL	26.54 mL
2	25 mL	26.51 mL
3	25 mL	26.60 mL
4	25 mL	26.49 mL
5	25 mL	26.57 mL
Average	25 mL	26.54 mL

Buret because it has the smallest increments.

Graduated Cylinder because it is closest to the actual answer

Graduated Cylinder because it rounds to a whole number

Buret because it is closest to the actual answer.

The Buret is the most precise tool because it has the smallest increments of measurement. The measurements shown by the Buret are more precise compared to the measurements shown by the Graduated Cylinder. The average measurement of the Buret is 26.54 mL, which is the closest to the actual answer of 25 mL. Therefore, the Buret is the most precise tool in this scenario.

Explanation

The Buret is the most precise tool because it has the smallest increments of measurement. The measurements shown by the Buret are more precise compared to the measurements shown by the Graduated Cylinder. The average measurement of the Buret is 26.54 mL, which is the closest to the actual answer of 25 mL. Therefore, the Buret is the most precise tool in this scenario.

8. In the pendulum lab, it was important that we began by....

Making a hypothesis

Making observations

Checking precision of testing instruments

Generating a testable question

In the pendulum lab, it was important to begin by making observations because this step allows us to gather information about the pendulum's behavior and characteristics. By carefully observing the pendulum's motion, we can identify patterns, measure variables such as the length and amplitude, and note any anomalies or irregularities. These observations serve as the foundation for forming a hypothesis, generating testable questions, and ultimately conducting experiments to test our predictions.

Explanation

In the pendulum lab, it was important to begin by making observations because this step allows us to gather information about the pendulum's behavior and characteristics. By carefully observing the pendulum's motion, we can identify patterns, measure variables such as the length and amplitude, and note any anomalies or irregularities. These observations serve as the foundation for forming a hypothesis, generating testable questions, and ultimately conducting experiments to test our predictions.