Posts tagged education

Featured Teacher: Meg Marsh

Name: Meg Marsh
School : L.C. Swain Middle School in Greenacre, Florida
Subject(s) you teach: Full Sheltered ESOL Reading/Language Arts
Grade Level(s): 7th and 8th Grade

How Meg uses educational rap in and out of the classroom:

Our school, L.C. Swain Middle School, is a six year old Title One school in Greenacres, Florida, about 30 minutes (and a whole world away) north of Boca Raton. It is about 55% Hispanic, 30% African-American /Haitian, and 15% everything else.

We are an “A” rated school because we have continually improved with each year of our existence, meeting the necessary requirements to advance, but 75% of our population is on free or reduced lunch and many live in trailers or in multi family apartments.  I teach fully sheltered ESOL students (ESL up north), as there is a large population of English language learners in southern Florida. I love my kids!

Recent successes:

My students learn so well with music; and they told me that by remembering the lyrics to “Figurative Language” helped them with the many new poetry questions on the test this year - really!!

Anything that you’d love to have people know: 

My students are going to make a video of their performance, which they are presenting to parents for our ELL Multicultural Party in May. 

You have a great product and I look forward to using it more , in new and different ways!

From RRR:  We’re so glad to hear of your successes with RRR in your fully-sheltered ESOL classrooms.   We’re looking forward to seeing the video, and wish you and your students the best for their performance at the ELL Multicultural Party in May!

Casting Out Nines

Sweet multiplication trick. Don’t let the “mod 9” stuff throw you. Read this, then try a couple examples yourself.

“Casting out nines” is an elementary check of a multiplication which makes use of the congruence 10^n=1 (mod 9). Let decimal numbers be written a=a_n...a_2a_1a_0,b=b_n...b_2b_1b_0, and their product be c=c_n...c_2c_1c_0. Let the sums of the digits of these numbers be a^*, b^*, and c^*. Then a=a^* (mod 9), b=b^* (mod 9), and c=c^* (mod 9). Furthermore ab=a^*b^* (mod 9), so c=c^* (mod 9). So if c and a^*b^* are incongruent (mod 9), the multiplication has been done incorrectly.

For example, 12345×67890=838102050. The sum-of-digits of 12345 and 67890 are 15 and 30, respectively, and the product of these is 450. Similarly, the sum-of-digits of 838102050 is 27. And 450=27=0 (mod 9), so the check shows agreement.

Casting out nines is also an addition test, since a+b=a^*+b^* (mod 9)), and a subtraction test, since a-b=9+a-b (mod 9). It can also be used as a division test for a/b=q+r/b (i.e., a=qb+r) since a^*=q^*b^*+r^* (mod 9).

Casting out nines was transmitted to Europe by the Arabs, but was probably developed somewhere on the Indian subcontinent and is therefore sometimes also called “the Hindu check,” with “Hindu” simply meaning the people of the Indian subcontinent.

The procedure was described by Fibonacci in his Liber Abaci (Wells 1986, p. 74).

source: Weisstein, Eric W. ”Casting Out Nines.” From MathWorld—A Wolfram Web Resource.

mathworld.wolfram.com

Just found this video on YouTube this morning.  Great job to every one in Mrs. Preis’ class!