## Friday, November 6, 2015

### Math: practice in addition and subtraction

In math class we practice adding and subtracting in a wide variety of ways.  Along with what we learn in the Singapore books, there are many ways we practice these skills.
Here are a few:

We start math class sitting on the perimeter (a great math word) of the green rug.  While we are there, we practice skip counting by various numbers.  We have gotten pretty good counting up, but counting down is a bit tricky.  This directly correlates with our proficiencies in adding and subtracting.  Adding seems to be a much easier task.

Here are a couple examples of games we play with addition and subtraction:

"I have..."

Each child gets a card. One person starts by reading their card. For example:

I have 14.
Who has 15-8?

The person with the answer  (in this case 7)  reads their card.

I have 7.
Who has 18-9?

And so it goes until we get back to the first person.

"What number are you on?"

A child starts on the zero rectangle and moves forward or backward over the dotted path.   I tell them how many steps to take forward or backward.  They have to tell me what number they are standing on.
 Dots from zero to 20

There are many stories that help us learn math skills.  Counting Crocodiles by Judy Serra is a favorite.  In the story a monkey counts the crocodiles in the Sillabobble Sea.  "One crocodile with a great big smile.  Two crocs resting on rocks...  And ten crocs dressed like Goldilocks."   At the end the crocs ask, "How many, then are we?".  The monkey answers: "Just enough to make a bridge across the Sillabobble Sea, but not enough to catch a clever monkey like me!"   The answer is not given in the story, so we had do a lot of adding to figure out there were 55 crocs.