Tuesday, March 1, 2016

Decimal Fractions, Part Two

We have continued our work with decimal fractions. Some of the cubes in this box will look different than they did the last time you saw them because I spray-painted them.  The two colors of blue and two colors of green provided by the manufacturer (Kid Advance) were embarrassingly similar.  The cubes I sprayed are the lightest blue and the lightest green.  One could, if they were ambitious, spray paint all the cubes so that the match the colors on your decimal board.  I've looked at images of the Nienhuis material and it's hard to tell but it looks as though it is done that way.  While I'm mentioning this type of thing, I am still not convinced that the box for the cards shouldn't be arranged more like a bank game box.  I could buy an extra bank game just for the box but we'll see how I feel after using the material a while.  I also had to modify our decimal board as you'll see further on.

I couldn't help including this.  Truman, our dog, has learned to sit at the mat whenever it looks like Mom is going to give a presentation.  #montessoridog

I gave a presentation with the Bank Game cards in which you line up the cards above the tens, hundreds, thousands, etc., and then pivot them by grabbing the left edge and pulling it in an arc over to the right.  Then, you place a decimal point after the first zero.  This helps demonstrate the "reflection" on either side of the decimal point.  I can't STAND manipulating little pieces of card stock so instead of hole-punching the decimal points we used pony beads.

I showed them the decimal board next.  We placed the category beads and cubes in their appropriate places and "crowned" the unit.   This board is printed on wood.  It is glossy.  It works fine with the cubes but terribly with the category beads.  They roll all over the place unless you are able to stand them carefully on their holes.  I got my board for a few dollars when ordering other things years ago.  You should really just make this out of felt.  I noticed in the Eric Johnson videos that their board has a felt surface and a frame.

I love the little crown I found.  It has jewels.  It sparkles.  Enough said.  Many "ooo's" and "ahhh's" from the boys.  It's single-handedly making the whole decimal work super compelling for them.  

We also use this pinwheel to demonstrate that the decimal system is balanced with the unit in the middle or revolves around the unit.

My candelabra didn't turn out exactly like I wanted it but does the job.  The candelabra demonstrates the relationship of categories on each side of the decimal.  We also draw their attention to how the colors are darkest on the left-hand side of the board and lightest on the right-hand side of the board.  We tell them that the darker the  "flame" is on the candelabra, the higher the number; the lower the flame, the lower the number.

Okay, so here you can see I have felted our board.  I just applied white glue with a paintbrush, added the felt and drew lines on with a permanent marker.  I used black felt to put a thicker line at the decimal point and also to hide the seam between the two pieces of felt I had on hand.  You could use a larger piece of felt if you felt like going to the store.  There was a snowstorm here so I stayed home.  The boys were very vocal about their admiration of the board with the added felt.  

We started by placing quantities of nine or less in a single category, finding the matching number card, and reading the number.  Then, we moved on to putting a quantity of more than nine in a single category, exchanging, finding both number cards, and reading the quantity.

Kal-El was determined to use every cube in the box.  He was hoping to force the exchange from the tenths to the tens but there are only sixty cubes in the box for each category.


  1. Oh, yay for the personalized exploration...Kal-El, using all the cubes. T was just like, okay, yeah, mom, new categories, I - got - it...what's next? Sometimes I wish he'd dwell a bit more. I have a feeling that D is going to be just like T in this way.

    Sooo cute to see Truman learning decimal fractions!

  2. I love your amazin explanation, as always@@ this its my new math material! very helpful!! hugs