Grade 4 Maths

[tcofran]

Am i a blithering idiot ? or am i just over complicating things this morning ? or is turning 40 in 5 months finally catching up ? My daughter is writing Grade 4 maths today and asked me this question this morning at 6.....

there is a dam. around the dam there are ducks and cows. There are 39 heads, and 98 legs...... How many cows are there ?:erm:

 

[mo_mia]

oops

 

[mo_mia]

10 (cows) x 4 (legs) = 40
29 (ducks) x 2 (legs) = 58

so 39 heads and 98 legs.

 

[syntax]

working out

4x +2y = 98 (x = cows)
x + y = 39

x = (39 - y)

4(39 - y) + 2y = 98
156 - 98 = 2y
y = 29

x = (39 - 29)
x = 10

 

[Cheri_N]

Since when do kids need to do algebra at grade 4? (I think we probably only started multiplying by then). And we only got introduced to algebra in grade 8!

Poor kids!

 

[mo_mia]

The education system is failing! High school maths is not preparing kids for university!

Oh no, they are making the kids do algebra too early!

 

[Cheri_N]

The education system is failing! High school maths is not preparing kids for university!

Oh no, they are making the kids do algebra too early!

FFS, Algebra is too difficult for a child that age... I don't think they are mentally capable to understand it yet.

 

[mo_mia]

See dequadin's example above. The actual question is not so difficult that we shouldn't be teaching it to kids that age. I also think you grossly underestimate what kids are capable of learning.

 

[Cheri_N]

Really?

Are you a parent? Are you a clinical or educational psychologist? Logic dictates that a child that young is incapable of learning complex mathematical equations.

Just to clarify: I did not say that the question is too difficult for grade 4 maths, but introducing algebra in grade 4 is unreasonable.

 

[mo_mia]

Logic dictates?

I'm not really going to argue this with you. Perhaps ask around these forums at what age posters or their kids were capable of algebra. Have a guess at what age schoolkids in China and India learn this stuff.

 

[Cheri_N]

I disagree.

Knowledge required to solve this problem:

1. Every animal has one head
2. Cows have 4 legs
3. Ducks have 2 legs
4. Addition
5. Multiplication

Insights required to solve this problem:

1. The number of ducks + the number of cows = 39
2. 4 * number of cows + 2 * number of ducks = 98

While technically this is algebra, so is "If Bobby has twice as many apples as Alice, and there are 6 apples. How many apples does Bobby and Alice have?"

When you only use the "divide, multiply, subtract, add" (arithmetical operations) without the confusing (for kids at least) x & y variables, it becomes acceptable.

 

[mo_mia]

dequadin's posts in this thread explain it well. I think it's the word algebra that has triggered your reaction.

 

[Cheri_N]

Logic dictates?

I'm not really going to argue this with you. Perhaps ask around these forums at what age posters or their kids were capable of algebra. Have a guess at what age schoolkids in China and India learn this stuff.

So I gather you are neither.

 

[R13...]

I'm not sure if this is sarcasm...?

In high school people used to call maths solving for x and for some reason this really scared them & left them shocked for life. Maybe that's what's happening here? A bad case of childhood "solve for x" gone very wrong.

 

[Johan449]

I wonder if this ain't maybe the solution that they wanted the kids to use (doubt they do algebra at such a young age):

39 heads
98 legs

39 heads * minimum 2 legs per animal = 78 legs
98 legs - 78 legs = 20 legs left over
20 legs /2 legs = 10 cows

Thus 10 cows & 29 Ducks

 

[Cheri_N]

I wonder if this ain't maybe the solution that they wanted the kids to use (doubt they do algebra at such a young age):

39 heads
98 legs

39 heads * minimum 2 legs per animal = 78 legs
98 legs - 78 legs = 20 legs left over
20 legs /2 legs = 10 cows

Thus 10 cows & 29 Ducks

Thank you.

 

[Johan449]

@Johan449 Nice solution, I hope you don't mind it I re-word it quickly.

2(c+d) = 78
98 - 2(c+d) = c/2
c/2 + 2c + 2d = 98
(5/2)c + 2s = 98       - (1)
 
c + d = 39             - (2)

(2) into (1)
c/2 = 20
c = 10

QED

not at all

poor children

 

[TheHiveMind]

39 x 4 = 156 (legs if all heads belong to cows)

infact, we only have 98 legs so..

156 - 98 = 58 (legs which belong to ducks)
58 / 2 = 29 ducks

39 heads - 29 duck heads = 10 cow heads

ED::Ya, what johan said..

 

[tcofran]

I wonder if this ain't maybe the solution that they wanted the kids to use (doubt they do algebra at such a young age):

39 heads
98 legs

39 heads * minimum 2 legs per animal = 78 legs
98 legs - 78 legs = 20 legs left over
20 legs /2 legs = 10 cows

Thus 10 cows & 29 Ducks

I agree with Johan449 on this one... and thanks for all the info guys / girls

 

[Mike Hoxbig]

Really?

Are you a parent? Are you a clinical or educational psychologist? Logic dictates that a child that young is incapable of learning complex mathematical equations.

Just to clarify: I did not say that the question is too difficult for grade 4 maths, but introducing algebra in grade 4 is unreasonable.

Why does everything always have to turn into 'are you a parent'? Just because you've shagged and popped out a kid doesn't magically make you more qualified to judge what's best for all kids. What if the 'educational psychologist' doesn't have any kids?

Yes the algebraic part involving simultaneous equations to solve the problem is probably not grade 4 level, but 'problem sums' as they're called in primary school most certainly is. I recall having to do similar problems when participating in maths olympiads in primary school, so it's not altogether unreasonable. Refer to Johan449's answer as to why it isn't.

But I forgot, I'm not a parent &| an 'educational psychologist' so my opinion is hogwash

Just to clarify: I didn't see any mention of introducing Algebra to grade 4 kids.