Teaching Addition and Subtraction

My book, Almost Unschooling Grama, is getting there. I was thinking it would be about 50 pages long, but I'm at page 44 and still have a bit to go. Might be more like 60 or 70 by the time I am through! This an excerpt from it about how I teach kids to carry in addition and borrow in subtraction. I've been helping my granddaughter with math. She's not really quite ready to do the subtraction step yet, but I pushed her yesterday just so I could get her artwork. Thank you Kathy for putting up with Grama!

Ball Factory

When I asked my adult kids to tell me some of their favorite activities, my oldest boy didn't even have to think about it. “BALL FACTORY!”

I was having problems getting my kids to understand the concepts of place value, carrying and borrowing. (Sorry, I'm old school - not sure what the new math terms are.)

So I told my kids to imagine the big balls that they sell at Wal-Mart. We were going to pretend we work in a factory where they are made. 10 of these balls will fit into a great big box and 10 boxes fit into a truck. Our job is to pack the boxes and the trucks.

Then we draw our factory.

I make the columns with the balls, boxes and trucks and then put the numbers we want to add on the left hand side. I tell them we have been working in the factory for the last 3 days and we need to see how many balls we have made.

First we draw the balls (the numbers in the ones column). Once we have all the balls drawn, we x out and circle groups of 10 to put in boxes in the box column. Once we've filled all the boxes that we can, we count the number of balls that are left over and put that number in the ones column in the answer. Then we count the number of boxes that we filled and put that number above the tens column.

Then we draw the boxes (the numbers in the tens column). We count the boxes to see if we can make any trucks. If we can, we x them out, circle them and put them in a truck. We count any boxes we have left over and put that number in the tens column. Then we put the number of trucks in the hundreds column.

When they are able to add three four-digit numbers this way, I add in a three digit number or two and a warehouse column. Once we've got 10 or more trucks ready to go, we drive those puppies right over to the warehouse and fill it up!

To teach subtraction, I tell the kids we have an order from a store! We need to gather up the balls that they need so we can fill the order. We start with the ones. If we don't have enough individual balls to fill the order, then we need to empty a box. We cross out a box and then draw 10 balls over in the ball column. Then we circle the balls we need to fill the order and write the number we have left in the ones column of our problem. We cross out the number we have in the tens column of our original number of balls and write the number of boxes we have left above it. Then we move on to the boxes and do the same thing.

Some kids catch on to the ball factory quickly and get bored with doing all that drawing, opting to do the calculations with just the numbers in a few weeks. Others take longer,a and still others just really love drawing the balls, boxes, trucks and warehouses. I let them continue playing in the factory a long as they want to, but I do encourage the artists to do some problems without the aide of the factory :)

Does this make sense to you?

God Bless You All!

~Grama Sue