How Many Days?
How many days are there between February 25th 2000 and March 11th?
Age
5 to 7
Challenge level
How many days were there between February 25th 2000 and March 11th ?
What does 'between' mean?
Should we count the starting and finishing days? Why?
Should we count the starting and finishing days? Why?
Deniz from IRMAK Primary and Secondary School, Turkey says, "We can't count February 25th and March 11th because it says 'between'.
From 26th day to the 29th day of February, (29th day included) there are 4 days. 2000 is a leap year - that's why February takes 29 days.
From 1st day to the 11th day of March (11th day excluded) there are 10 days. The sum of these numbers is 14 days."
Why do this problem?
For young children
this problem is not as trivial as it first sounds. The
difficulty in visualising or reciting the names of the months in
order and how many days there are in each will probably lead to
some sort of recording or need to look at a calendar or diary. At
some point the discussion will involve deciding just what is meant
by 'between'.
Possible approach
It would be helpful if this coincided with work on sequencing
the months of the year and learning the number of days in each
month. Encourage children to discuss the question first in small
groups and decide on what they think the answer might be. Then
allow them to examine a Year 2000 calendar or a diary. Should they
count the starting day and finishing day? Does knowing the starting
day is a Friday and the finishing day is a Saturday help work out
the answer? There is also the fact that February 2000, being a leap
year, has 29 days, to discuss.
Key questions
What does 'between' mean?
Should we count the starting and finishing days? Why?
Possible extension
Once interpretations have been agreed upon, ask the children
to pose their own similar questions for others to answer. What if
the year was the current year? Could we work out the answer without
going back to the beginning?
Possible support
Large calendar pages that can be written on may be helpful.
And discussion is always important!