To be a bit confused about DD's science homework?

[Nibledbyducks]

DD has just started year 6 and came home with science homeork on classification. One of the fill in the blank questions ended up as "mammals give birth to live young but birds lay eggs". Ok I know they start with the basics but why not "mammals give milk to their young"? what about sharks? and monotremes? surely it's best to be accurate from the get go?

[Nibledbyducks]

We talked about how the lesson they had built on the basics an how living things were originally classified in ways that we now know aren't quite right because of genetics and things we have learnt through the fossil record. We talked about why we classify living things. I totally understand that starting with the basics is the right thing. But in the same lesson they were given a list of animals and groups to put them in which included tadpoles but only sea creatures as an option to put them in, and then we got this homework. My daughter has been to a zoo and seen an echidna, and she's raised frog spawn from her first school pond, I'm sure there's plenty of children who have done the same, so she was just as confused as I was.
As for being elitist, I think it's more elitist to assume that science is such a difficult subject that you have to be highly intelligent to understand it.

[babybythesea]

Yes that would make a difference (both being bright and being Australian!)
Because in the UK this comes into the curriculum with five and six year olds, some of whom won't be able to read properly, or who may have really limited contact with any kind of animal, it's a gentle starting point which can be taken further if the kids can cope.

[Tezza1]

Babybythesea:
Yes, my 8 year olds were all quite bright and perceptive - the school was academically streamed and these were the top of six classes, so they were able to get their brains around a lot of things (as I said this was a fair while ago. I don't know if any schools in the system still stream children this young).

Additionally, because they are Australian, they were all very familiar with marsupials and monotremes, and completely appreciated the differences.

[glueandstick]

Biology is just chemistry, chemistry is physics and physics is maths. The only certain thing is maths. Maths never lies. Oh. Wait.

Everything is a living lie!

[babybythesea]

Tezza - yes, great. I found doing it with Year 1s though that the best stage was to let them actually do it. So heap up a massive pile of skins, feathers, snake sheds etc (as well as using real animals, just not in the pile!) and let them physically feel them all and then sort them out into different points in the classroom. If they then ask about dolphins etc, great, and you can mention it. But at that stage, I am just happy with them getting to grips with the basic principle - exceptions can come later (lie your Year 3s.)

Incidentally, it can get very complicated.
All mammals feed young on milk.
So what about doves and pigeons? They feed their young on the lining of the throat which they regurgitate - it's called crop milk. Does that make them mammals? No, clearly not. So is it that mammals feed on milk by the mammary glands? Because the monotremes don't have mammary glands - they ooze it from a bald patch near their groin. So are they now not mammals?
Ultimately classification is not a clear cut topic because the living world is not a clear cut place. Classification is an artificial attempt by us to make some sense of the world around us.
Try defining the word species, for example. We all know what a species is but there isn't a good definition that covers all options. So do we say that to kids? Nope. We give them a broad definition which is broadly accurate and then gradually introduce the anomalies to ponder on.

Same with classification. These big artificial lines we want so badly to be there, in the main, just aren't. They are in our heads. But there are things which annoyingly don't fit the patterns.

So let's discuss the broad patterns, because by and large the vast majority of mammals do have fur and do produce live young and do feed babies milk. And then let the kids process that idea, and get a handle on the whole concept, including why we do it, and make some sense out of it. And then if they are ahead enough to ask, or if they have pretty much got their heads around it, introduce the animals which don't fit nicely into the box, or provide information based on things they can't easily see or imagine.
Patterns are important even if there are exceptions but if you start with 'this is mostly true but this animal doesn't fit and neither does this one or this one' the kids will start to feel like nothing fits so why even bother!

[EmergentFaction]

Just popping in to say nice thread. Interesting!

And nice post babybythesea

[Soubriquet]

The only thing that could cover every branch of mammal is that they feed them on their own milk

[Tezza1]

Now, let's look at a dolphin, no fur - how do we explain this being a mammal? By the end you can be saying 'mammals tend to...' Rather than 'all mammals have.... '
As I mentioned earlier, the lesson in classification that my class was given at the zoo (8 year olds), was that mammals have hair or fur at some stage in their life, even if it's only before birth.

[babybythesea]

I teach classification in my job (teach educational groups visiting a relevant institution so cover all ages from nursery to uni groups).

I've done this job for almost 20 years and have played around with both curriculum requirements but also the best way to introduce and expand on these things across the age ranges (allowing for the fact that I only see the kids as a one-off, so while I teach year 1 and year 6 classification it's not the same kids progressing through, if that makes sense, so there is some variation in background understanding).

Vertebrate classification is Year 1.
I do it on the basis of visible characteristics, asking 'What is this animal covered in?'
We do it through first hand experience - touch the fur, describe it, compare it to the snake skin etc. As a classification system it's not perfect but it's a start. If the class asks about animals that don't seem to fit, we can explore that, or if their understanding is good enough. But we also cover why we do this - it's as important to get a handle on why classification is important as it is on how to do it.

Bit later on and we do invertebrates vs vertebrates - and look inside a tortoise shell to see the spine, look at a bat x-Ray, look at and handle mini beasts. And then relate it back to what they already know - how does this fit with the bird reptile mammal thing you already know? Can you remember how to do that bit? Let's refresh and go a bit further with how we group those animals.

The trouble is, any statement used to define a group of animals can almost always be undermined with exceptions. Almost any statement in science in fact. So how do you teach it? This is important and these are the rules but they don't work? So you start with broad statements and ideas and as kids get their heads around it you develop the ideas further. Mammals have fur. Fact. Let's let everybody think about that, experience it, take it in, it's broadly true a d they can broadly speaking see it for themselves so apply it in every day life (that dog has fur, it's a mammal). Now, let's look at a dolphin, no fur - how do we explain this being a mammal? By the end you can be saying 'mammals tend to...' Rather than 'all mammals have.... ' But it's a gradual process.

It's easy as an adult who did science at a high level to see your way through apparent contradictions but lots of kids struggle and then switch off if you start with the the 'I'm telling you how complicated this is' approach right from the start.

Does that make sense?

[BestZebbie]

valency: teaching that all mammals give birth to live young isn't just a simple version though, it is factually inaccurate, as it erases a whole branch of mammals (including the duck-billed platypus, which is famous enough for most children to have heard of it, often in the context of animal fact books which say that it lays eggs).
I agree that also seems a bit strange to use that example instead of milk or hair, which are actually unique characteristics of mammals (though I guess they were just trying to distinguish birds from other everyday animals)

[acasualobserver]

It's possible to take too much interest in your child's homework.

[valencyrules]

Yes YABU and this is why some of the most brilliant science graduates make terrible teachers. They pick holes in everything and just can't bring themselves to simplify concepts to allow 'less gifted' minds to access their subject.

Some - actually many - in that class will never have a hope in hell of understanding the intricacies of chemical bonding etc, but by learning a simple set of valency rules and applying them they may be able to write and interpret the meaning of chemical formulae. They won't get A* in GCSE Chemistry or even consider A level.

It's sometimes worth telling more able students that some explanations are just a construct or simplification, but your viewpoint is elitist and a little offensive IMO.

I really hope you're not a teacher.

[Tezza1]

Surely not. Dolphins don't ever have fur.
Apparently baby dolphins are born with whiskers which fall out soon after birth. So, they do fit that type of categorisation, which, as I said, may well be out of date.

[RhiWrites]

one of the defining things for a mammal is fur at some stage in their existence, even if it was pre-birth.

Surely not. Dolphins don't ever have fur.

[titchy]

Sweat it...

[titchy]

I wouldn't swear it - scientists don't use that classification system anyway. It's about 100 years out of date!

[Tezza1]

Surely mammals are called mammals because they have mammary glands?
At a zoo excursion (Sydney's Taronga Zoological Park) my class was told that one of the defining things for a mammal is fur at some stage in their existence, even if it was pre-birth. This was in an exercise in categorising vertebrates, and used the body covering as a criteria. Saying that mammals give milk to their young is accurate, but eggs to categorise birds doesn't take into account monotremes (which lay are mammals that lay eggs and are covered with fur and also produce milk) like the platyus and echidna.

This was a fair while ago, and methods of categorising may well have changed since then.

[sixandoot]

ie - all mammals give birth to live young (true)
Yeah, but that's not true.

[topcat2014]

I think the phrase is necessary but not sufficient.
ie - all mammals give birth to live young (true)

whilst

all animals that give birth to live young are mammals (false).

I remember struggling with electron shells at GSCE - my scientist parents were no help, as they started from the fact that the whole premise wasn't really true. - Didn't help me though :)

[Igneococcus]

I think with some concepts you need to start with a broader, less detailed picture and then add on. Like you couldn't teach photosynthesis in its full and fascinating detail without knowing a hell of a lot of chemistry, physical chemistry, biochemistry, physics but you need to know what photosynthesis is and roughly how it works long before you have that knowledge.

[contortionist]

The statement in your DDs homework isn't wrong, although it isn't the definition of either a bird or a mammal. The most general statement would be "vivaporous animals give birth to live young; oviparous animals lay eggs" (although that still doesn't cover all sharks ) - but that then becomes a empirical-content-free definition.

[KeyserSophie]

Wait till they get onto the blue eye, brown eye thing, OP, you'll be inconsolable

[Igneococcus]

I never used valencies in Chemistry A level but did at GCSE, why not just learn about electron shells and bonding to start with?
How do you do chemistry without valancies?
I remember a thread on a different site where someone asked a question about something her child learned at school and it seemed they were still being taught the five kingdom system of life, nobody besides me thought this to be a problem.

[contortionist]

But electron shells isn't a correct quantum
mechanical description either. You have to start somewhere!

[OwlinaTree]

I've never heard the term monotreme, nice words though, I'm looking forward to a chance to use it. Do you think you might be over complicating this homework?!

I'm guessing you are a scientist?