Focus!

Scientific American: Beyond IQ: Youngsters Who Can Focus on the Task at Hand Do Better in Math
Attention span and reasoning may get higher marks than intelligence, especially in math

I have often noted, as a high school math teacher, a direct relationship between a student's ability to focus and persevere through a lesson and/or problem and what they ended up learning, retaining, and what grades they earn. Attention span and follow-through seem to be real issues affecting students' learning, and not just for those with diagnosed ADD or ADHD.  One of the key factors to attain this is that people who have a growth mindset, rather than a fixed mindset, can perform and focus better.  A growth mindset is one that is focused on personal improvement.  A fixed mindset views math ability (or other abilities) as genetic or innate or left or to fate, and thus students think their math performance is 'out of their hands'.

When Can You Reuse This Year's Calendar?

Let us first assume that you are only interested in which dates fall
on which days of the week; you are not interested in the dates for
Easter and other irregular holidays.

Let us further confine ourselves to the years 1901-2099.

With these restrictions, the answer is as follows:

- If year X is a leap year, you can reuse its calendar in year X+28.

- If year X is the first year after a leap year, you can reuse its
calendar in years X+6, X+17, and X+28.

- If year X is the second year after a leap year, you can reuse its
calendar in years X+11, X+17, and X+28.

- If year X is the third year after a leap year, you can reuse its
calendar in years X+11, X+22, and X+28.

Note that the expression X+28 occurs in all four items above. So you
can always reuse your calendar every 28 years.

But if you also want your calendar's indication of Easter and other
Christian holidays to be correct, the rules are far too complex to be
put to a simple formula. Sometimes calendars can be reused after just
six years. For example, the calendars for the years 1981 and 1987 are
identical, even when it comes to the date for Easter. But sometimes a
very long time can pass before a calendar can be reused; if you happen
to have a calendar from 1940, you won't be able to reuse it until the
year 5280!

Source and for more info:

http://www.faqs.org/faqs/calendars/faq/part1/