New School Year - September 2011

Welcome Back!
That's all for now...

First Decimal Correction!

Hello!
  Today I had my first opportunity to correct a sign with an incorrect decimal point.  I was at my beloved Allendale farm and noticed a chalk sign by the register stating Honey Stix .25¢.  With some encouragement from J I turned the little chalkboard around and asked, "Is it alright if I am an obsessive math teacher and fix your sign?" The woman behind the register said, "oh my goodness, that says a quarter of a cent! Please fix it." Score one for the Decimal Project! She then said, "you should have asked for change back from a penny."  A woman after my own heart!
  If you look carefully at the picture below you can see two smudges - one where I accidentally put my thumb on the "y" of Honey and another where the decimal before the 25¢ used to be.  The staff at the registers also said they'd look around the farm stand to fix the other signs.  Next time I'm back that the farm I'll have to check to see if the signs have been corrected.

Our First Student Decimal Project Submission

I arrived back from lunch yesterday to find two empty containers of cookies on my desk.  My reaction was, "who left trash on my desk?!?"  When DA, aka Aggie, came to my room he said that a student, LM, had left them there.  When LM arrived I asked him why he felt he could leave the cookie containers on my desk and he replied, "the prices are wrong!" I was so focused on the trash, I had never looked at the label. 
Here are the photos of the cookie containers in question:

 

69.  and 70

  

LM hit on a topic I hadn't even covered - the lack of ANY label for monetary unit.  We can (hopefully) assume that the store means to charge 69 cents and 70 cents for said cookies, but how do we know?  There is no label.  As I ask my students who fail to label their work in class, "what do you mean?" 70 shoes? 69 ice creams?  No label = reduced credit for a problem.  

Nice work LM!!

Report Cards - Again!

We just finished another Marking Period.

  3rd MP:  January 31, 2010                                 April 15, 2011 (Tax Day!) ✔

     - Please bring in your absence notes if you have any absences to make sure you get a grade and not an incomplete mark. (YM & JV, that means you!)
     - Report cards will come after vacation, probably the week of May 1st - 7th.

  4th MP:  April 25, 2011                                    June 28, 2011 (Report cards are mailed home.)

      Warning notices will be filled out on May 20th to let you know how you are doing in your classes.  If you have any concerns, please see your teachers BEFORE this date to help improve your grade.

Decimal Points - Find 'em, photograph 'em, and fix 'em!

  I have recently noticed an increase in the improper use of decimals in the signs around my community. Stores of countless variety, even large chains, are incorrectly pricing objects or perhaps offering outrageous deals. Considering not one store has offered me change for my proffered penny I must conclude that the signage is incorrect.
  Case in point note the signs in the Portland, ME fishmonger's shop at left.
.75¢ per clam, but 90¢ per oyster.

Do you notice the difference?

                                                                 Look carefully.
  Oysters are selling for a little less than $1.00 each. Ninety cents per oyster. That seems reasonable, right?
  Clams are going for .75¢ each. At first glance this may seem as though the clams are 15¢ less than the oysters.  Not so.
                                 .75¢ means that the clams are less than a penny each!

Not a bad deal, eh?

My goal is to find, photograph, and make an effort to fix any such signs that I come across. I also want to encourage my students, my friends, and decimal-conscious strangers to do the same and to post about it.
The math blog isn't the place to keep track of all of this "mispointage" so in the coming weeks I plan on creating a blog site wiki "place to vent my frustration at this mathematical mess" devoted to the cause.  In the meantime feel free to comment or provide me with pics to post on the "Decimal Project" page of Kate's Math Class.
(Students in my class can earn points or possibly tasty treats for good images of decimal errors!)

Countdown to HS Math MCAS

Hai's Binary Tree

Check out the awesome binary (powers of two) tree that Hai drew in school.

 

So cool, eh?

Notice how the trunk of the tree becomes the 1 for the numerator of all the negative powers of two.

Ex. 1/2 ; 1/4 ; 1/8 ; 1/16... 

Midterm Time! (High School)

Topics:
   - Order of Operations (there are pictures on the picture page)
   - Pattern of Terms/Distributive Property (also pictures on the picture page)
   - area and perimeter (use your "best friend" papers)
   - Time facts
   - Multiplication, division, and squares/roots

Below are some examples we did in class (time facts and multiplication/division/squares are not here):Click on the picture to make it larger!