## Friday, February 19, 2016

### Decimal Fractions

We started a new thread of work this week, decimal fractions.  We got through the first several presentations and then paused because I realized I needed the number cards from the bank game and I sold it.  I needed some things from Alison's anyway and they are super quick.  The new bank game will be here on Monday and then we can continue.  You also need some hierarchically-colored beads (not bead bars) for these demonstrations.  If you happen to have the box of beads that go with a small square root board like we did that would be perfect, otherwise you can cannibalize your racks and tubes.

We used the fraction circles to demonstrate that the unit divided into ten equal pieces creates "tenths" and introduced the hierarchically-colored wooden cubes.

I was super frustrated that my decimal cubes, from Kid Advance, are not really the right colors.  One album I have describes the six colors of cubes as "light blue, lighter blue, pink, light pink, light green and lighter green."  I would have settled for "blue, red, green, light blue, pink, and light green."  Instead I have two dark blues so close in color only a Montessori primary child fresh off color box three could distinguish them.  The greens aren't much better.  As this is the third time in the past few weeks I've discovered that materials specifically from Kid Advance, while undamaged and passed my initial inspection, are not always made to Montessori specifications and not necessarily usable. Edited to add:  I had a great customer service experience with Kid Advance today, and they didn't know I was a blogger.  Everything has been rectified.   I think I will break out the spray paint this weekend and lighten up one set of blue and one set of green cubes.

Eventually we reached the point where the boys could talk me through this progressing either to the left or to the right of the unit bead in the center something like as follows:  a unit divided into ten equal pieces becomes tenths, one tenth divided into ten pieces becomes hundredths, one hundredth divided into ten pieces becomes thousandths, etc.,  OR a unit multiplied by ten creates a ten, a ten multiplied by ten becomes one hundred, one hundred multiplied by ten becomes one thousand.  Next week when I have everything available I can introduce the number symbols.