Project Math Access DVD 02 - Abacus- Part 01
Transcript Start
Audio Description: Part one; abacus logic method; addition.
TEACHER: Okay, today we're going to do a little review of the Logic Method. And Peter is going to describe for us how to do an addition problem, subtraction, multiplication and division. But before we get started, I just want to bring up the fact that there are numerous ways to teach the abacus, but I would say the most popular ways are the Secrets Method and the Logic Method. And we're going to just really concentrate on the Logic Method today. The Logic Method is a method that if you have a student who really understands the workings of math, that‘s the way I would go. If you have a student that might be a little less able to understand the reasons for things and is a very rote learner, I would recommend the Secrets Method. Now with Logic, the student should really have a good understanding of fact families because that's kind of what you're dealing with when you're going to be setting and clearing your numbers on the abacus. And I'm not going to go any further with this but Peter's going to explain to us where to set the numbers and what the thought process is for him to work through these problems. And I've got some problems right here. We're going to start; if you need to look back you can look back here.
PETER: Alright, cool.
TEACHER: But let's start with a money problem. $195.70 and you're going to want to add $8.51 to that.
PETER: Alright, so I'm going to start by using my first unit mark as my decimal place. And to the left of the unit mark, I'm going to set 195. Set 195. And the unit mark is my decimal so immediately after the unit mark I would set 7 for (point).7. That's the tenths place, immediately to the right of the unit mark. And I want to add $8, well 8.51, $8.51. So first I will go to the ones column and see if I can add 8 there, which I cannot do directly and I can't add 10 directly and I can't add 50 directly, so I'll have to add 100, which is 98, 92 too many. So I'll clear 90 and for my 5, I'm going to...
TEACHER: And you're back in your ones.
PETER: Back in the ones column, and I can't clear 2, so I'll clear 5 and set 3.
TEACHER: Which is how many too many?
PETER: Which is 2 too many, so I'll set 3. And there's the 8 and to add (point).51, we go immediately to the right of the unit mark and we can't add (point).5 directly, so we will add 1, which is (point).5 too many, so we can take away (point).5. And the 1 in the hundredths place, which we can add directly and we will. And our final answer is $204.21.
TEACHER: Okay, that's right.
PETER: Cool. And I'll clear the abacus.
TEACHER: Okay. So in that particular problem, he set directly. He also had to use his fact families not only for 10, which means going to the next column, and then coming back to the column he actually is trying to do the adding in. But he also had to go over a couple of columns.
PETER: Borrowing from different columns and carrying those numbers over.