# Math Mammoth 4A--Time Units

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Did anyone else find some of the problems in the Time Units chapter to be rendonkulous and nitpicky? For example, in one problem the student is supposed to find out how many days are in a century ... but the answer varies depending on what year you start with, and the student is supposed to use this complicated set of rules to determine whether a year is a leap year. Nowhere could we find an explanation of why the year 2100 will not be a leap year, even though there is a leap year 4 years before and 4 years after. We know the rule, but we don't know why a leap year would be skipped.

I also don't like that she gives instructions to include the beginning date when counting how many days are from one date to another date. For example, if I were to give the number of days from today (12/8) to next Thursday, I would say 7. The MM author's answer would be 8. I was always taught not to include the starting date. Then her rule of including the starting dates doesn't hold true when calculating elapsed time in hours and minutes. 2 1/2 hours after 3:40 is 6:10, according to her answer key (and my calculations), but according to her "include the starting date/time" rule it would be 6:09.

Dd worked on these problems for over an hour and was in tears. I finally told her to forget it because they seemed needlessly complex. Am I the only one? FWIW, I got all the "How much time has passed?" questions wrong because I didn't include the starting date.

Tara

Edited by TaraTheLiberator
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I set it aside after doing the "how many days from this date to this date" section. We could do them, but they did seem very tedious and annoying. I hated those problems. My son hated those problems. We moved on to long division, which we both enjoyed much more!

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I used the time unit from 3B and don't plan to use the 4A unit. We practice daily out loud now, and will continue to do so. I'll randomly ask him the time, then tell me a couple ways of saying it. Then how long until (X) time. If DS enjoyed doing those worksheets I'd let him, but he is clock fluent and that is all I care about with that one!

As far as calendar dates, you have to tell specifically if you plan to include today, or AFTER today. I have a different text for wordy type problems because i can't stand the wording of those in MM. Our calendar time said "Not counting today, how many days is ....."

Edited by 425lisamarie
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Technically, a day is 24 hours. If you're counting days, you would start with the first 24-hour period, which would not include the starting day but the next. Thus, Thursday to Friday is not two days but one because it is only one 24-hour period.

We are using MM but haven't gotten to that section yet. Thanks for the heads' up. I'll teach my kids to count the days NOT using the starting date, no matter what the answer key says.

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We're working on this unit right now. Where it instructs to include the starting date, we just included it by adding 1 to the answer. For the how many days in a century, we just divided 100 by 4 = 25 leap years, added that to the total days and left it at that. Maybe that isn't quite accurate but I wasn't interested in spending a boatload of time on figuring it out exactly. :) And for the problems that seemed needlessly nitpicky and beyond my son, we just skipped. So far I think we've only skipped one problem but we aren't that far into it either.

I must say, it's fun to find other people working through MM 4 and to find that we're all on the same chapter. :D

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I'll teach my kids to count the days NOT using the starting date, no matter what the answer key says.

Make sure you black out the instructions for number 5 (a and b) on page 138 because it tells the children specifically to include the starting and ending days. I wish I would have looked more closely at this stuff before dd agonized over it. It's not worth the anguish. ;)

Tara

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Make sure you black out the instructions for number 5 (a and b) on page 138 because it tells the children specifically to include the starting and ending days. I wish I would have looked more closely at this stuff before dd agonized over it. It's not worth the anguish. ;)

Tara

Thanks. I'll definitely watch out for that.

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Did anyone else find some of the problems in the Time Units chapter to be rendonkulous and nitpicky? For example, in one problem the student is supposed to find out how many days are in a century ... but the answer varies depending on what year you start with, and the student is supposed to use this complicated set of rules to determine whether a year is a leap year. Nowhere could we find an explanation of why the year 2100 will not be a leap year, even though there is a leap year 4 years before and 4 years after. We know the rule, but we don't know why a leap year would be skipped.

All 00 years except those divisible by 400 are not leap years. Those divisible by 400 are leap years.

This is a correction to the assumption that the earth takes 365 1/4 days to orbit the sun.

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