Q&A - P3 Science

[IJJ]

zuluwarriors1879:

http://postimage.org/image/2706cpdms/


Can anyone help suggesting an answer? I suspect the answer in the assessment book is either wrong or the question is poorly formulated.

Thanks.

3.

[IJJ]

zuluwarriors1879:

http://postimage.org/image/1vgqx55hg/


Can anyone help suggesting an answer? I suspect the answer in the assessment book is either wrong or the question is poorly formulated.

Thanks.

The%20pencil%20lead%20and%20fifty-cent%20coin%20sunk.%20I%20think%20this%20question%20is%20very%20subjective%20to%20the%20size/surface%20area%20of%20the%20objects.%20Not%20quite%20a%20good%20question,%20IMO.

[S6169]

Please help for this question. Thanks!

http://postimage.org/image/2xds40lt0/
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My answer is 4 because air can be compressed.

[S6169]

deleted

[gel]

teh_oh:

S6169:

no choice, must follow teacher's answer. sometimes feel difficult to explain to our kids.

Hi,
I posted your question to my child and he immediately said that his teacher told the whole class not to simply write 'living/non-living thing' as the answer for such questions. They were told to state characteristics or what are their physical attributes (eg bat vs bird, both have wings).
Science is indeed tricky. :roll:

The question is similar to a question in My Pals are Here - Diversity P3&4 - pg11. The question in the textbook asked \"WHY are Zoe (cat) and Teddy (toy) so different?
The answer given in the textbook:-
They are different because Zoe is a LIVING THING and Teddy is a NON-LIVING THING.

[IJJ]

zuluwarriors1879:

IJJ:

[quote=\"zuluwarriors1879\"]http://postimage.org/image/1vgqx55hg/


Can anyone help suggesting an answer? I suspect the answer in the assessment book is either wrong or the question is poorly formulated.

Thanks.

The%20pencil%20lead%20and%20fifty-cent%20coin%20sunk.%20I%20think%20this%20question%20is%20very%20subjective%20to%20the%20size/surface%20area%20of%20the%20objects.%20Not%20quite%20a%20good%20question,%20IMO.

Having said that, I checked the internet which said that lead is dense (I presume greater than water) so it will indeed sink. And if it is a coin, it is made of metal whose density would be greater than water. Therefore, it will also sink.[/quote]The question asked \"Circle the wrong ticks...\" so, we tried to spot existing 'ticks' that should not be there. For copper if it is hard or not? My girl said, they were taught copper is metal, so relatively to other materials such as cotton, sponge etc, it is hard. Relative to other metals like iron, aluminium, it is not. In this, it should be relative to other non-metal materials as stated. When I asked my girl on the question, she immediately took a pencil lead to try the sink/float experiement and it sank.

Ok, if my jelly mind did not fail me, I ever read in her text that the hardness of a material is refering to the ability of keeping its shape while being hammered. Correct me if I am wrong. So, if there is the case, then a coil of copper wire, yes, it should be hard, but just a cable itself... :?

[atutor2001]

IJJ:

.... that the hardness of a material is refering to the ability of keeping its shape while being hammered. Correct me if I am wrong. So, if there is the case, then a coil of copper wire, yes, it should be hard, but just a cable itself... :?

Hardness is determined by scratching the surfaces. If material A can cause a scratch on material B, then A is harder than B.

\"Malleable\" is the property that determines if a material will \"Keeping its shape after being hammered\"

[IJJ]

atutor2001:

IJJ:

.... that the hardness of a material is refering to the ability of keeping its shape while being hammered. Correct me if I am wrong. So, if there is the case, then a coil of copper wire, yes, it should be hard, but just a cable itself... :?

Hardness is determined by scratching the surfaces. If material A can cause a scratch on material B, then A is harder than B.

\"Malleable\" is the property that determines if a material will \"Keeping its shape after being hammered\"

Thanks for correcting my mistake.

[atutor2001]

zuluwarriors1879:

Therefore the Moh test is used...but as I mentioned before copper's Moh is 3. So can it be described as hard or do we accept all metals as being hard?

In Pr Science, most common metals are considered to be hard (maybe with the exception of lead and mercury).

The 2 wrong ticks are :

\"Wooden ruler is waterproof\" because wood is not waterproof.
\"Fifty cents coin float\" because metal cannot float.

[atutor2001]

zuluwarriors1879:

Thanks that is what I thought but is lead denser than water and hence will sink?

The density of lead is higher than water. However, since it is specified as pencil lead, its mass is very small and can stay on the water surface due to \"surface tension\", (unless a push force is applied to break the surface tension and it will sink). Though it is not in Pr Science syllabus, at times, such observation skill of things around us can be tested. Another example would be pepper powder remaining on the surface though its density is higher.

For such cases, I used to tell my kids to pick the best answers.