Educational worksheet on time zones with a world map and related questions.

Here are the answers to the questions on the worksheet, based on the map provided.

1. Through which oceans does the International Date Line pass?
Looking at the thick black line labeled "International Date Line" (which is also the 180° longitude line), we can see it runs vertically through two large bodies of water. At the top of the map, it passes through the Arctic Ocean. As it goes down between Asia and North America/South America, it passes through the Pacific Ocean.

2. When it is 4:00 A.M. in Portland, what time is it in Sydney?
* First, find Portland on the map. It is in the Pacific Time Zone (marked with a P).
* Next, find Sydney, Australia. It is in the time zone marked with an S (or sometimes labeled +10 or similar depending on the specific map version, but here it is clearly to the right).
* Count the time zones moving East (to the right) from Portland:
* Portland (P) to Mountain Time (M) = +1 hour
* Mountain (M) to Central (C) = +1 hour
* Central (C) to Eastern (E) = +1 hour
* Eastern (E) to Atlantic (A) = +1 hour
* Atlantic (A) to the next zone (often labeled for South America/Eastern Canada) = +1 hour
* Crossing the Atlantic to Europe/Africa zones = +1 hour per zone.
* Let's count the steps directly on the map grid from P to S.
* Portland is roughly UTC-8. Sydney is roughly UTC+10.
* The difference is 18 hours.
* If it is 4:00 A.M. in Portland, add 18 hours.
* 4:00 A.M. + 12 hours = 4:00 P.M.
* 4:00 P.M. + 6 more hours = 10:00 P.M.
* So, it is 10:00 P.M. in Sydney on the same day.

*(Self-Correction/Verification: Let's double check the map's specific zones. Portland is in the 'P' zone. Sydney is in the zone labeled 'S'. Between them are roughly 18 hour-steps eastward. 4am + 18 hours = 10pm. This assumes they are on the same calendar day, which they are if you travel East from morning in the US.)*

3. When it is 9:00 P.M. in Tokyo, what time is it in Rio de Janeiro?
* Find Tokyo. It is in the time zone just west of the International Date Line (often UTC+9).
* Find Rio de Janeiro. It is in Brazil, on the east coast of South America (often UTC-3).
* To go from Tokyo to Rio, you can go West across Asia and Europe, or East across the Pacific. Let's go West because it's easier to subtract hours without crossing the date line backwards.
* Tokyo is roughly UTC+9. Rio is roughly UTC-3.
* The total difference is 12 hours (9 + 3).
* Since Rio is West of Tokyo, it is earlier in the day.
* 9:00 P.M. minus 12 hours = 9:00 A.M.
* So, it is 9:00 A.M. in Rio de Janeiro.

4. What does this difference in time suggest about the location of the two cities?
The fact that there is a significant time difference (12 hours in the previous example, or 18 hours in question 2) suggests that the cities are located far apart from each other in terms of longitude (east-west direction). Specifically, they are on nearly opposite sides of the Earth. When one side of the Earth faces the sun (daytime), the other side is facing away (nighttime).

Final Answer:
1. Arctic Ocean and Pacific Ocean
2. 10:00 P.M.
3. 9:00 A.M.
4. It suggests that the two cities are located on opposite sides of the Earth (far apart longitudinally).