Time of completion (Times Tables)

[Moonbear]

If he can figure out how to multiply by applying the concept that it's addition, does he really need to be able to quickly regurgitate the times tables? I don't think I ever learned my times tables (to this day, I have to stop and think about things like 8X7). Between being moved from one math class to another as they realized I was smarter than they expected for whatever reason, and then being moved to a different school when we were redistricted, I skipped some of those more tedious lessons. While I was always very slow with my math problems, I would still score 100% on tests regularly. I wouldn't worry so much about how fast he can recite a times table, but instead focus on accuracy. I think if he can figure out the answers without memorization, it will set him up for much better lifelong learning. Maybe he'll prefer the frog dissection anyway.

 

[Integral]

I taught my step son the multiplication tables while driving him to school. We had about a 15 min drive and I just kept quizzing him as I drove. I went through the tables pretty much in order until he learned the patterns, then began to mix it up so he had to know the answer. I am with Chi, I think there is a lot of value in being able to spit out such facts without having to figure it out from scratch each time. Such exercises are good for brain function and as confidence builders. It is distressing to me at how low our expectations are of American students. Higher expectations cannot do anything but cause higher performance.

Why shouldn't some 4th graders be learning Algebra? Not clear that ALL 4th graders are ready but there are some that are. Currently elementary school teachers are to a high percentage math phobes themselves, to have then teaching math is criminal.

 

[moose]

Have you taught him methods like when multiplying by 5 you can just half and multiply by 10, etc?

EDIT: I just remembered when I learned these. We were quizzed extensively on multiplication tables in 3rd grade. My teacher placed huge emphasis on being able to pass her timed trials, so every now and then I would memorize the tables/find patterns and such worried that I'd be the only one in the class who didn't pass them. Turns out I was the only one to pass her timed test of it and that's how she plans it out, making it "impossible" to make us do the best we can. It was a good confidence booster because I moved to the US in 3rd grade and knew 0 english at first.

Also, I know a few people who would take 5 seconds to tell you that 6x7 is 42. That's just weird.

EDIT2: This, somehow, reminds me of my roommates friend who is in Calc 2 at the local community college, and wasn't able to tell us what a derivative at a point looked like graphically. Somehow he passed Calc 1 with a B though. So yes, memorizing things is definitely stupid unless you actually understand what you're memorizing as well.

 

[Chi Meson]

Have you taught him methods like when multiplying by 5 you can just half and multiply by 10, etc?

That's the basic stuff. I'm still fascinated by multiples of 9. Take any multiple of nine, and add the digits. THey add up to nine. If the sum is more than 1 digit, then add the digits of the sum, and that adds up to nine.

 

[rootX]

That's the basic stuff. I'm still fascinated by multiples of 9. Take any multiple of nine, and add the digits. THey add up to nine. If the sum is more than 1 digit, then add the digits of the sum, and that adds up to nine.

I loved the tables of 1,2, 5, 9,10, and 11..
(for 11 also discovered that:
11*12 = 11+22
11*13 = 11+33
)
9 has always fascinated me too :)

Other reason for loving 9:
Start from 0 to 9 .. and then write 9 to 0 in reverse next to each digit

09
18
27
3.
4.
5.
6.
7.
8.
90

As for memorization or learning, I think there's no match for experience and practice with one thing. I see many people expecting to understand things without any practice...

And Personally, I think learning is one of the easiest job in the world - you need only one thing: time! And, there's no risk. You input your effort and you learn.

 

[mgb_phys]

Have you taught him methods like when multiplying by 5 you can just half and multiply by 10, etc?

I still remember in junior school (age 7-8?) standing up and explaining to the teacher that we didn't need to learn all these times-tables because as long as you knew what 2x, 5x and 10x was then it was easy to work out all the others.

(Yes I was that kind of child - I think they breathed a sigh of relief when I left.)

 

[rootX]

I still remember in junior school (age 7-8?) standing up and explaining to the teacher that we didn't need to learn all these times-tables because as long as you knew what 2x, 5x and 10x was then it was easy to work out all the others.

Like
3x6 = (1+2)x(1+5)?

Then, you don't even need to know any table
3x6 = (1+1+1)x(1+1+1+1+1+1)

 

[Chi Meson]

Then there are clever paper calculator tricks, like this
http://www.youtube.com/watch?v=8Mcl3empKkY&feature=related
and this
http://www.youtube.com/watch?v=zK_HmQcuSp0&feature=related

 

[Jimmy Snyder]

That's the basic stuff. I'm still fascinated by multiples of 9. Take any multiple of nine, and add the digits. THey add up to nine. If the sum is more than 1 digit, then add the digits of the sum, and that adds up to nine.

The same procedure works for 3. The proofs are rather satisfying and simple to do.

 

[Chi Meson]

Proofs? Oh, no. That's magic, that is.