4. Scientists have noted that at present the Earth is closest to the sun in January and farthest from the sun in July. The reverse will be true in 13,000 years and the Earth will then be closer to the in sun in July than January. How does Earth's current proximity to the sun affect the climate in the
Northern Hemisphere? (3 points)
Winters are cooler and summers warmer because of the closer proximity of the of of Earth to the sun.
• Winters are warmer and summers cooler because of the closer proximity of the Earth to the sun.'
O Winters are shorter and summers longer because of the closer proximity of the Earth to the sun.
Winters are longer and summers shorter because of the closer proximity of the Earth to the sun.

1. the question asks the most appropriate, which seems to rule out "all of the above." your choice appears to be the correct one.

2. the protocol described is good for identifying correlation, but not cause and effect. for cause/effect, you need to devise a protocol that will assign the treatment (or not) to groups that have essentially the same "demographics" with respect to all the other variables. your choice regarding control group seems appropriate. random assignment of treatment (choice d) may be appropriate also. (i think you can argue that b and d are just different descriptions of the same method.)

3. d will randomize the birds, but may not guarantee there are 10 in each group. e will do both, so seems the better choice.

comment on question 2

based on the problem statement, it seems clear that confident, attentive drivers are more likely to use daytime running lights. so, the protocol might need to be devised in such a way that the lights would be turned on or off without the driver's knowledge. (an attentive driver will figure it out.) assigning a confident, attentive driver to a group required to drive without running lights might mess with his/her confidence and attentiveness. you don't want your experiment to do that. (nor do you want the experiment to subject a driver to greater risk of accident as a consequence of driving without running lights.) experiments involving human safety are always problematic.

answer by yourhope:

how do models compare to real-world objects?

d. most models represent a real-world object in a simpler way.

: )