negative numbers

[Ember58]

DD (13) has struggled with maths since starting high school 2 years ago (we are in the uk). She has visual processing difficulties and recently diagnosed with ADHD but generally keeps up academically (and sometimes does very well). Since starting on concerta and a very low dose of risperidone, her general learning, including maths, has come on in leaps and bounds. Last year (before the meds), she really could not 'get' negative numbers - we tried using vertical and horizontal number lines as well as good old fasion maths 'rules'. This term (semester?) they are learning algebra and she is , for once, really getting it and even enjoying it BUT the lack of understanding with negative numbers is really holding her up she really doesn't get that -4 + 12 is 8 and that is the same as 12 - 4...I'm stumped (and I'm a maths teacher!) but really need to do some remediation with her so that she can keep flying through algebra...any ideas?

[peacefully]

I am NOT a mathy person, so take this advice with a grain of salt. Could you explain negative numbers in terms of the Celsius temperature scale? This was a very concrete explanation for me, since I could grasp that a negative number was even colder than the temperature at which water freezes. Adding a negative number meant that the temperature was getting colder, adding a positive number meant that the temperature was getting warmer.

 

I also just want to mention that after a while I didn't need to constantly picture blue and yellow. ;) Well... sorta. :tongue_smilie:

 

Edited to add:

I guess this was easier for me because I just could not figure what what could be less than nothing. I could, however, figure out colder than 0°.

Edited September 22, 2010 by yllek

[Guest]

The temperature analogy is a good one; money also works. Talk about debt or spending and savings or earning. You can use a pile of dollar bills to illustrate.

[Mom22ns]

MUS did two things I liked. The first was to explain positive and negative numbers in the terms of what I get and what I owe. Using that terminology helped a lot. The other thing was to show that a negative sign means "opposite". So if a number is positive and has a negative sign, it becomes negative. Another negative sign make it the opposite again - positive. They show this by taking the blocks which are hollow on the back and showing them forward, then turning them over for each negative. If you have one positive and one negative after you have done all your flipping, the open holes cover the closed front and you can see the number remaining. If both are positive or both are negative, they just add up.

 

I don't know if you any manipulatives that can work the same way, but between the explanation and the manipulatives we are golden!

[Ember58]

Thanks - that's really helpful, especially the stuff about the manipulatives. I do have the MUS manipulatives and also the delta series. Do you know which series he covers negative numbers in as DD got on really well with MUS when we did the delta series together a few months ago...

 

Yesterday they were multiplying out brackets in algebra and she did a whole page correctly - I was SOOOO pleased especially when she said 'It's so easy'. I've NEVER heard her say anything about maths was easy before. Let's hope she gets negative numbers as easily when i put my hard hat on and give it another go with her!

[Laura Corin]

I taught my boys using the table top. The table top represents 0, above 0 is above the table top, below 0 is below the table top. Somehow the table made sense where number lines didn't.

 

Laura

[Laurie4b]

in Stand and Deliver, the teacher used the illustration of digging a hole . The measurement of the hole is a negative number, the level of the ground is 0 and the sand piled on top is a positive number.

[Mom22ns]

Thanks - that's really helpful, especially the stuff about the manipulatives. I do have the MUS manipulatives and also the delta series. Do you know which series he covers negative numbers in as DD got on really well with MUS when we did the delta series together a few months ago...

 

Yesterday they were multiplying out brackets in algebra and she did a whole page correctly - I was SOOOO pleased especially when she said 'It's so easy'. I've NEVER heard her say anything about maths was easy before. Let's hope she gets negative numbers as easily when i put my hard hat on and give it another go with her!

 

It is done in pre-algebra, right at the beginning.

[HeidiD]

The concept clicked when we used this number line marker board in conjunction with problem-solving.

 

http://www.rainbowresource.com/product/Student+Number+Line+Markerboard+-20+to+%2B20/014077/1285371326-1162247

[MerryAtHope]

Thanks - that's really helpful, especially the stuff about the manipulatives. I do have the MUS manipulatives and also the delta series. Do you know which series he covers negative numbers in as DD got on really well with MUS when we did the delta series together a few months ago...

 

Yesterday they were multiplying out brackets in algebra and she did a whole page correctly - I was SOOOO pleased especially when she said 'It's so easy'. I've NEVER heard her say anything about maths was easy before. Let's hope she gets negative numbers as easily when i put my hard hat on and give it another go with her!

 

It is done in pre-algebra, right at the beginning.

 

In fact, iirc the online sample demo for pre-algebra is a lesson on teaching negative numbers. I can't remember if that's the one where he shows how the manipulatives work though. I find his explanations very helpful!

 

Merry :-)

[melmichigan]

Have you watched the Muggins Math prealgebra for visual learners video? http://www.mugginsmath.com/store.asp if you scroll down the video link is at the bottom after all the games.