QOD—Monday, August 29

1. QOD—Monday, August 29 • Tell which statements describe a hypothesis. (may be more than one answer—choose all that apply) • It is the result of many experiments • It is a possible answer to a question • It is a question • It can be tested by experimentation or observation.

2. Answer • B and D are qualities of a hypothesis. • A) a hypothesis is made before the experiments and directs the type of experiments done. • C) a posed question may LEAD to a hypothesis to test.

3. Answers to HW • Mass: solid food items, people, and mail; Volume: liquid food items and gasoline; Length: rope, distance, height

4. Answer to HW #2 2. The scientific method involves critical thinking in that it entails thinking about a problem and making objective judgments about results.

5. HW Answer #3 3. A hypothesis is a possible answer to a question that can be tested. An example would be, “I can pass the test if I study at least 5 hours.”

6. HW Answer #4 4. No experiment should be called a failure because an experiment that produces unexpected results provides a chance to learn something new.

7. HW Answer #5 • There are still scientific theories that have not been verified, because the tools needed to test these theories do not yet exist.

8. HW Answer #6 6. An SI-based unit is a single unit while a derived unit is a combination of base units. Base units include: seconds, meters, kilograms, Kelvin, amperes, moles and candelas. Examples of derived units include meters squared (m2) or meters cubed (m3).

9. HW Answer #7 7. It is much easier to determine which factor your experiment depends on if you only check one factor at a time. If you change more than one thing and something unexpected happens, you will not know what caused the result.

10. QOD Tuesday, August 30 Which statements are hypotheses? EXPLAIN your answer(s). • Cockroaches are repelled by cucumber slices. • Leos are luckier than Capricorns • Ajax beige wall paint fades more quickly than Supreme beige wall paint • Newton was the greatest 18th century scientist.

11. Answers • A and C can be tested by established scientific methods. • B cannot be tested. • D is an opinion.

12. QOD • How do scientists report their results and conclusions to other scientists? • Scientists can share information by publishing articles in scientific journals, by giving oral or visual presentations at science meetings, and by using the Internet.

13. 1. Describe the kind of data that is best displayed in a line graph? • Line graphs are best for continuous change.

14. 2. Describe the kind of data that is best displayed as a pie chart. Give example Answer: Pie charts show the parts of a whole. An example is the percentages of types of CDs that make up a collection.

15. 3. Explain in your own words the difference between accuracy and precision Answer: Accuracy is how close a measurement is to being correct. Precision indicates the reproducibility of the measurements or how close the measurements are to each other. Precision can also show how many decimal places were in the measurement.

16. 4. Critical Thinking: An old riddle asks, Which weighs more, a pound of feathers or a pound of lead? Answer: The correct answer is that both weigh the same. A reason for an incorrect answer might be that mass is confused with volume, and a given volume of feathers would be much lighter than the same volume of lead.

17. 5. Convert the following measurements to scientific notation • 15, 400 mm3 1.54 x 10 4 mm3 b) 0.000 33 kg 3.3 x 10-4 kg c) 2050 mL 2.05 x 103 mL d) 0.000 015 mol 1.5 x 10-5 mol

18. 6. Calculate the following: • 3.16 x 103 m x 2.91 x 104 m = 9.2 x 107 m2 b) 1.85 x 10-3 cm x 5.22 x 10-2 cm = 9.66 x 10-5 cm2 c) 9.04 x 105 g / 1.35 x 105 cm3 = 6.70 g/cm3

19. 7. Calculate the following and round to the correct number of sig figs. • 54.2 cm2 x 22 cm = 1,200 cm3 b) 23,500 m / 89 s = 260 m/s