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#1
11-06-2006, 06:54 PM
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Need a good trick to teach kids about adding negatives and positives.
Tutoring kids in Math is so much fun. I really enjoy doing it. Its interesting noticing almost every one of my students has the same problem. They can do all the work, but when it comes to adding/multiplying/dividing negatives and positives they ALMOST all have a problem with it. Each session the kids learn alot the way I teach it but I find the next time I go back they are making the same mistakes and it is with adding these. I'll make up problems and one of example would be -19 + 7 and sometimes the kids will say +12 or -26 etc.
What I've been teaching is "If you have the same sign, add them and keep the sign" and "If you have different signs subtract them and keep the higher sign". When that doesn't work I draw the absolute value line graph and try to show them. I wondering if anyone has any good little tricks so I can make this clearer to the kids. Thanks. 
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#2
11-06-2006, 06:57 PM
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Re: Need a good trick to teach kids about adding negatives and positives.
Integer line, boardgame approach, in the case of -19 + 7, try to make clear they start at -19 and have to move 7 spots to the right, in this instance -12. With enough time and patience, the approach will become faster and initutive for those students. if the + value is bigger, say -21 + 32, they'll learn to take away 21 spots and add 11 in the positive end.
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#3
11-06-2006, 07:03 PM
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Re: Need a good trick to teach kids about adding negatives and positives.
[ QUOTE ]
Integer line, boardgame approach, in the case of -19 + 7, try to make clear they start at -19 and have to move 7 spots to the right, in this instance -12. With enough time and patience, the approach will become faster and initutive for those students. if the + value is bigger, say -21 + 32, they'll learn to take away 21 spots and add 11 in the positive end. [/ QUOTE ] Ya I've been doing the integer line (i called a line graph for some reason).. I feel like when I do that its making it so much more confusing for the kids. I was naive going into this. When I left the first student I figured it was just him. Now as I go house to house each kid has the exact same problem. Kinda weird.
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#4
11-06-2006, 07:38 PM
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Re: Need a good trick to teach kids about adding negatives and positives.
It isn't natural to think of numbers as having negatives and positives. When you find yourself counting things and have to correct a count because one item's missing, if you sense a slowdown and a gap in logic when you adjust, that's a natural effect. Man isn't supposed to be able to think in these terms, and that has to be learned. Yeah, it's weird. Don't worry, someone'll come along and discredit negative numbers. That's SMP for ya. [img]/images/graemlins/tongue.gif[/img]
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#5
11-06-2006, 07:50 PM
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Re: Need a good trick to teach kids about adding negatives and positives.
If they can do 19 + 7, and they can do 19 - 7, then when they see 7 - 19, and the second number is bigger, tell them to flip it around to 19 - 7 which they know how to do, and then make it negative at the end. There's no need to tell them to "keep the higher sign", because they aren't having trouble with 19 - 7, and you don't want to confuse them about something they already know how to do.
Then when they see -19 - 7, they can also flip that around and do 7 - -19, and if they know that the 2 minus signs makes a plus sign, this is 7 + 19, and make it negative at the end. So in both cases, when they see a subtraction problem they don't know, they can flip it around, and make it negative at the end. This is for subtraction. For addition, when we flip it around we don't make it negative at the end. So -19 + 7 is the same as 7 + -19. Then if you tell them that adding a negative (+ -) is the same as subtract (-), they should be able to do any addition or subtraction with positive or negative numbers. So 7 + -19 becomes 7 - 19, which they handle as above.
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#6
11-06-2006, 07:53 PM
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Re: Need a good trick to teach kids about adding negatives and positiv
MONEY MONEY MONEY!!!
Kids understand real-life situations much easier. Negatives and positives seem foreign, but the idea of owing money or receiving money is relatable. Simple pos-pos and neg-neg should be easy with this method, and pos-neg is much easier. Say, "You owe $10 to Jim, but Bob decides to give you $4. How much do you owe or have?" This will usually work.
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#7
11-06-2006, 08:01 PM
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Re: Need a good trick to teach kids about adding negatives and positives.
Ok. I have 2 sessions tomorrow. These tips should work. Bruce I did try what you said about flipping it around. I thought that would be the easiest way. What I have to do is find 1 way that works for everyone and stick to it.
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#8
11-06-2006, 09:54 PM
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Re: Need a good trick to teach kids about adding negatives and positives.
I'm with Fortuna. I've been teaching a basic math course for the past few years and have the same problem that you are. The integer line ("number line" for younger students) has been the most successful tool. I don't even use the board game setting, though that seems perfectly valid. I give each student a small dry erase board (finally graduated from pencil and paper), we draw the line and numbers as a group, and then practice problems by erasing or adding to the line as needed. Hope this helps.
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#9
11-06-2006, 09:57 PM
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Re: Need a good trick to teach kids about adding negatives and positives.
The boardgame principle seems to add entertainment value, and makes it fun.
And you should never underestimate that factor, although there is diminishing returns from that approach the older a kid gets. Bruce, your post confused me initially, how would you simplify it for a primary school student's capability to understand these concepts?
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