Reasoning · Grade 2-2 Time Zones and the Calendar
Problem
Seoul is 1 ahead of Beijing: 8 + 1 = 9:00.
'Ahead' means later, so the clock moves forward one hour from 8 to 9.
3.MD.A.1Work BackwardsDubai is 5 behind Seoul: 9 − 5 = 4:00.
'Behind' means earlier, so counting back five hours from 9 lands on 4.
3.NBT.A.2Work BackwardsVancouver gives 8 − 16 = −8, so add a day: 16:00, drawn at 4:00.
Going back more hours than the clock shows means wrapping past midnight into the previous day, so add 24 to keep a real time.
3.NBT.A.2Work BackwardsCounting back more hours than the clock shows wraps past midnight, so adding 24 brings the reading back to a real clock time.
A day is a closed cycle of 24 hours, so stepping off one end of it simply brings you back in at the other end.
Adding or removing whole days never changes the clock reading, so only the leftover part of a day decides what the clock shows.
Paris gives 16 + 9 = 25, so drop a day: 1:00.
Adding past 24 rolls over into the next day, so subtract 24 to read the clock time.
3.NBT.A.2Work BackwardsNew York gives 1 − 6 = −5, so add a day: 19:00, drawn at 7:00.
Counting back past midnight again means wrapping into the previous day, so add 24 to get a real time.
3.NBT.A.2Work BackwardsEvery time is on the hour, so all minute hands point to 12.
A 12-hour clock face cannot tell 4:00 from 16:00, so afternoon/evening times share the same hand position as their morning twin.
3.MD.A.1Draw A DiagramStart from the one clock you know and hop city to city: add hours when a place is ahead, subtract when it is behind, and wrap around by 24 if you pass midnight. Just Grade 3 add-and-subtract!