Son's teacher needs to go back to school

Poppy9

onlyroz wrote: »

In computing you might have something like:

if (30 > 60) then...

Such a statement would always return false because 30 isn't greater than 60 and never will be. It would still be a perfectly valid statement and the program would compile with no problems (doesn't mean that the person who wrote it wasn't bloody stupid though).

">" ALWAYS means "greater than", even if the expression using it is false.

This is the sort of IF statement I use on a spreadsheet except the number on the left would be a cell reference for it to test.

It is important that you know what the symbol means as it and I find I type it automatically but sometimes you doubt yourself so I always do manual check that the formula gives the expected answer.

I'm with the others

> is the greater than sign and < less than.

Sambucus_Nigra

onlyroz wrote: »

No it doesn't. It's what we call a comparison operator. If we've got a statement:
x > y
then from a maths or computing perspective it doesn't matter what x and y actually are. What we are interested in is whether the statement "x is greater than y" is true or false.

No, what we are interested in is whether the teacher is right when she says

">30" means "less than 30"

I say she's wrong. You say she's right but the statement is false.

Ho humm.....

onlyroz

Sambucus_Nigra wrote: »

No, what we are interested in is whether the teacher is right when she says

">30" means "less than 30"

I say she's wrong. You say she's right but the statement is false.

Ho humm.....

That's not what I'm saying at all. ">30" absolutely definitely means "greater than 30"

What I said was that "30 > 60" is a perfectly valid statement which returns false.

peaceandfreedom

Poppy9 wrote: »

Last summer when she was helping a friend with revision for her maths GCSE she asked me what something like 27 x 19 was and I spoke aloud going 10 x 27 is 270 so double it 540 and take away 27 = 513.

DD said yes I agree but I did 30 x 20 so 600 and then took 3 x 20 away so 540 and then took away 27.

Her friend was amazed we could both work it out in our head and our different methods. She attended a different primary school and said she had never really done mental maths.

I would have done 27 * 20 then subtracted 27. I agree, this sort of mental maths is so important. When my children were in primary school, the school held parent information evenings where they showed how they were teaching this kind of mental maths - pointing out, as you have done, that there are many quick routes to the correct answer.

Percentages are another example, I know plenty of people who could not even begin to calculate 20% of something, or 30% etc. They would struggle to do it with a calculator. If children are able to do this sort of mental calculation automatically, it helps them so much with the more complicated maths that they will tackle as they get older.

*max*

Sambucus_Nigra wrote: »

No, what we are interested in is whether the teacher is right when she says

">30" means "less than 30"

I say she's wrong. You say she's right but the statement is false.

Ho humm.....

You misunderstand I'm afraid. We are not saying the teacher is right, because she isn't. ">30" means "greater than 30". The teacher is wrong.

The expression ">30" in itself cannot be true or false because there is only one value.

It becomes true or false when another value is added to the left of the sign, as in "x>30".

Since the teacher says "25>30", the statement is false. Therefore she is wrong.

bestpud

Sambucus_Nigra wrote: »

No, what we are interested in is whether the teacher is right when she says

">30" means "less than 30"

I say she's wrong. You say she's right but the statement is false.

Ho humm.....

It cannot be right to read it as 'less than 30' because that is not what it says.

You say it matters where the 'greater than' sign is placed but it would still be read as 'greater than' if it was placed after the 30.

In that case it would be read as '30 is greater than' - still greater than!

There is no way the 'greater than' sign can become something else!

*max*

What an exciting way to spend a Saturday eh! lol

Sambucus_Nigra

*max* wrote: »

You misunderstand I'm afraid. We are not saying the teacher is right, because she isn't. ">30" means "greater than 30". The teacher is wrong.

I don't misunderstand.

I understand the symbols perfectly well, thanks.

But a > symbol only becomes a 'greater than' symbol when something is on either side of it.

So > on it's own is just a symbol. Once it has something on either side, then you can call it a 'greater than' symbol.....but on it's own it is meaningless. At the same time as it becomes a greater than symbol, it also becomes a less than symbol if the thing on the right hand side is the subject. It is both at the same time, as each are correct. Just because you read from the left and call it 'greater than' doesn't mean that someone reading from the right can't call it a 'less than' symbol.

30<60 can be said to be
'30 is less than 60'
as well as
'60 is greater than 30'

Both are correct. One may be used in computing as that's the way it scans, but you can't say the second is wrong, as it isn't.

That's my point about calling them 'greater than' or 'less than' symbols.

Bumpmakesfour

Sambucus_Nigra wrote: »

I don't misunderstand.

I understand the symbols perfectly well, thanks.

But a > symbol only becomes a 'greater than' symbol when something is on either side of it.

So > on it's own is just a symbol. Once it has something on either side, then you can call it a 'greater than' symbol.....but on it's own it is meaningless. At the same time as it becomes a greater than symbol, it also becomes a less than symbol if the thing on the right hand side is the subject. It is both at the same time, as each are correct. Just because you read from the left and call it 'greater than' doesn't mean that someone reading from the right can't call it a 'less than' symbol.

30<60 can be said to be
'30 is less than 60'
as well as
'60 is greater than 30'

Both are correct. One may be used in computing as that's the way it scans, but you can't say the second is wrong, as it isn't.

That's my point about calling them 'greater than' or 'less than' symbols.

THAT is what I was trying to say earlier.

bestpud

Sambucus_Nigra wrote: »

I don't misunderstand.

I understand the symbols perfectly well, thanks.

But a > symbol only becomes a 'greater than' symbol when something is on either side of it.

So > on it's own is just a symbol. Once it has something on either side, then you can call it a 'greater than' symbol.....but on it's own it is meaningless. At the same time as it becomes a greater than symbol, it also becomes a less than symbol if the thing on the right hand side is the subject. It is both at the same time, as each are correct. Just because you read from the left and call it 'greater than' doesn't mean that someone reading from the right can't call it a 'less than' symbol.

30<60 can be said to be
'30 is less than 60'
as well as
'60 is greater than 30'

Both are correct. One may be used in computing as that's the way it scans, but you can't say the second is wrong, as it isn't.

That's my point about calling them 'greater than' or 'less than' symbols.

So you think this teacher is teaching them to read from right to left then...

In mathematical language it means greater than.

It does have a figure either side of it in any case.

The 30 is one side and the pupil applies each of the other figures to that sum, therefore giving the sum two sides.