My Special Number: 25

For many years I assigned an end-of-unit project to my sixth graders titled My Special Number. This was when students would pick a number on which to perform a number study. Today I offer my own version of this assignment.

My special number is 25. It is a number that is described as odd, composite, and square. It is odd because it is not divisible by two. It is composite because its factor pairs are not only 1 x 25, but also 5 x 5. Having 5 x 5 as a factor pair is also what makes it a square number. In fact it is the smallest square number that is the sum of two other square numbers. ( 9 + 16 = 25) This relationship is found in many right triangles (known as 3-4-5 triangles) used for illustrating the Pythagorean Theorem.

Because 25 is a factor of 100, it is used in a variety of ways. A twenty-five cent coin is a quarter and it takes four to equal a dollar. 25% is equivalent to ¼.

The number 25 has significance in various religions and philosophies. According to Abellio, twenty-five is the symbol for the Universal Word of God. St. Augustin used it to represent the law. In the Bible, King Solomon builds a temple to God that is 25 cubits high, and a Levite could begin practicing his ministry at the age of twenty-five.

But today, the number twenty-five has a special significance. Today marks the day that indicates that FOR TWENTY-FIVE WONDERFUL YEARS I HAVE BEEN MARRIED TO THE BEST HUSBAND I COULD POSSIBLY HAVE!

The Daily Fraction

One ongoing activity that I like to do with my seventh grade classes is the daily fraction. This lends itself well to seventh grade because by then, students have been taught most fraction skills. There are a few that just didn’t get it, while some others have attained mastery, and the daily fraction works with both kinds of students. This activity takes about one minute a day and serves to review and for some re-teach a number of fractions concepts. It is a great point of discussion for students to notice and participate in.

I start at the beginning of the year by making a fraction template on a piece of white cardstock or construction paper. The template has the divide line with 180 as the denominator. I laminate it twice to withstand the daily write-on/wipe-off process. On the first day of school I use a dry erase marker to write a 1 as the numerator and say to the class, “When you go home today, one one-hundred -eightieth of the school year will be completed.”

On the second day, the one has been erased and a 2 is in its place. I ask the students to reduce the fraction and they realize that 1/90 of the school year is completed that day. We compare the two fractions noting that 1/90 is greater that 1/180.

Many days I ask the students to write the reduced form of the fraction on the back of their warm-up sheet, then discuss implications. I might ask them how close to 1/8or 1/4 of the year we are (midterm progress reports or report cards). I might ask for the percent of the year that has gone by or the fraction that is left.
Seventh-graders like to keep track of the year’s progression. Some years, students have felt that the year zoomed by and other years, it seemed very slow to them. But every day they are getting a little reminder of fraction skills through this number study.

So today is the 166th day of our school year. That's 83/90 of the school year completed with 7/90 to go. Or we could say that 92% of the year is finished with 8% left to complete. That translates to fourteen more days of school left!