Q&A - PSLE Science

[HDistinction]

Personally think that it is more important to let kids have strong foundation in Sc by referring to syllabus and using assessment books with typical qns, rather than using school past yr exam papers which hv some beyond syllabus qns (of latest craze? not to allow kids to score 100?!!)

If parents were continue to spoon feed kids with sch past yr papers of the latest craze, sch teachers may think that the kids can cope with these qns (but in fact, the kids hv done the qns bef their exam!!). That’s why some kids sc results were like ‘roller coaster’ --- scored high as they came across the qns bef exam but scored low if otherwise!!!
Always believe that as long as the kids have a good understanding of sc basic concepts, they can also handle the tougher qns in PSLE.
May be we parents should stop pushing kids to do a lot of past yr sch papers just bec of the few 'latest craze' qns which are beyond or out of syllabus but may also appear in their sch exam papers... in order to stop the craze???!!!
Good luck to all p6 kids. All the best.

[andante]

Hi,

For the question below, shouldn't the answer be (4) which is fleshing eating bird ?
http://i52.tinypic.com/2ij1a37.jpg\">

[Verysuperkiasu]

Weights hung progressively to two springs Y and Z and their lengths recorded as shown


Mass of weights Length Y (cm) Length Z (cm)
0 5 4
5 6 6
10 7 8
15 8 10
20 9 12
25 11 14

Qn then ask to plot graph… Based on the graph, explain why the extension of Y becomes greater when 25g of weight was added.

My question : My son says it has this to do with elastic limit? But I am not sure becoz elastic limit means it cannot go back to original length which is not shown in the table above.
Answer key : Spring Y has reached its maximum elasticity hence the increase after 25g weight was added was not constant anymore. Do you agree with this? And I’ve only heard of elastic limit not maximum elasticity. Are they the same?

[chrisu]

Both terms maximum elasticity and elastic limit are correct terms but different in meaning and usage.


Maximum elasticity is the limit of the spring that it stretch and yet still can go back to its original length, in this case should be less than 25g. So the text is not wrong to say it has reached its max. elasticity.

If deformation set in after 25g which is not shown in the experiment, then we can say 25g is the elastic limit of the spring.

So I would use the book answer for this question.

Elasticity and Elastic Limit
Elasticity of a body is the property of the body by virtue of which the body regains its original size and shape when the deformation force is removed. Most materials are elastic in nature to a lesser or greater extend, even though perfectly elastic materials are very rare.

From http://www.eduresourcecollection.com/civil_sm_Elasticity.php;
\"The maximum stress upto which a material can exhibit the property of elasticity is called the elastic limit. If the deformation forces applied causes the stress in the material to exceed the elastic limit, there will be a permanent set in it. That is the body will not regain its original shape and size even after the removal of the deforming force completely. There will be some residual strain left in it.\"

Verysuperkiasu:

Weights hung progressively to two springs Y and Z and their lengths recorded as shown

Mass of weights Length Y (cm) Length Z (cm)
0 5 4
5 6 6
10 7 8
15 8 10
20 9 12
25 11 14

Qn then ask to plot graph.. Based on the graph, explain why the extension of Y becomes greater when 25g of weight was added.

My question : My son says it has this to do with elastic limit? But I am not sure becoz elastic limit means it cannot go back to original length which is not shown in the table above.
Answer key : Spring Y has reached its maximum elasticity hence the increase after 25g weight was added was not constant anymore. Do you agree with this? And I've only heard of elastic limit not maximum elasticity. Are they the same?

[Verysuperkiasu]

chrisu:

Both terms maximum elasticity and elastic limit are correct terms but different in meaning and usage.


Maximum elasticity is the limit of the spring that it stretch and yet still can go back to its original length, in this case should be less than 25g. So the text is not wrong to say it has reached its max. elasticity.

If deformation set in after 25g which is not shown in the experiment, then we can say 25g is the elastic limit of the spring.

So I would use the book answer for this question.

Elasticity and Elastic Limit
Elasticity of a body is the property of the body by virtue of which the body regains its original size and shape when the deformation force is removed. Most materials are elastic in nature to a lesser or greater extend, even though perfectly elastic materials are very rare.

From http://www.eduresourcecollection.com/civil_sm_Elasticity.php;
\"The maximum stress upto which a material can exhibit the property of elasticity is called the elastic limit. If the deformation forces applied causes the stress in the material to exceed the elastic limit, there will be a permanent set in it. That is the body will not regain its original shape and size even after the removal of the deforming force completely. There will be some residual strain left in it.\"

Thank u for sharing!

[Verysuperkiasu]

Anyone can share about the swasthikaa answer keys for section A prelim 2011? My son didn’t agree with quite a few of them. Hope someone could verify…


Unfortunately I don’t have a scanner. One of them is as follows

Which of the following statements about the organism below are correct? Picture shows a frog.

A. It has many cells of various shapes and sizes.
B. It has cells which contain nuclei that pass hereditary materials down.
C. It has different cells to carry out different functions.
D. Cell division takes place as it grows.
E. It has some cells that are surrounded by cellulose walls.

(1) A, B and C only
(2) A, B and D only
(3) A, B, C and D only
(4) A, C, D and E only

Son’s answer is (3) but answer key is (2). Which is correct?

Qn 12 : Stephanie counted the no of plants & animals in her garden. Her findings are shown in the graph below.

No. of plants that grow on the ground = 10
No. of plants that grow on trees = 7
No of grasshoppers = 5
No of Lime Butterflies = 6
No of caterpillars of lime butterflies = 8

Based on the graph above (supposed to be a graph), which of the following statemets are definitely true?

A: There are at least 3 populations of animals
B: There are more plants than animals in Stephanie’s garden.
There are at least 2 populations of plants.
There is only one garden community

(1) A only
(2) B and C only
(3) C and D only
(4) A, C and D only

Son’s answer is (3) but answer key is (4)

[Verysuperkiasu]

Qn 13 Swasthika prelim 2011


The diagram below shows the various positions of a metal ball when released from point A. It swings to point D before coming to a stop at point B

Picture shows a metal ball suspended by a string. Position A is where the ball is at South west direction ie abt 45 degree, then it will swing to the other side D, drop to and finally to B which is vertically downwards which is at rest (but still suspended).

Which one of the following correctly describes the energy of the metal ball at A and when it finally stops at B?

(1) A= Potential energy B= Potential Energy
(2) A = Potential energy B= Kinetic energy
(3) A= Kinetic engergy B = Potential engergy
(4) A= Kinetic engergy B = Kinetic energy

Son’s answer is (1) but answer key is (2) Which is correct?

[atutor2001]

Hi Verysuperkiasu


My answers for the 3 questions are the share as your son’s.

[cimman]

HDistinction:

Personally think that it is more important to let kids have strong foundation in Sc by referring to syllabus and using assessment books with typical qns, rather than using school past yr exam papers which hv some beyond syllabus qns (of latest craze? not to allow kids to score 100?!!)

If parents were continue to spoon feed kids with sch past yr papers of the latest craze, sch teachers may think that the kids can cope with these qns (but in fact, the kids hv done the qns bef their exam!!). That’s why some kids sc results were like ‘roller coaster’ --- scored high as they came across the qns bef exam but scored low if otherwise!!!
Always believe that as long as the kids have a good understanding of sc basic concepts, they can also handle the tougher qns in PSLE.
May be we parents should stop pushing kids to do a lot of past yr sch papers just bec of the few 'latest craze' qns which are beyond or out of syllabus but may also appear in their sch exam papers... in order to stop the craze???!!!
Good luck to all p6 kids. All the best.

I agree with you. However, these days, the examiners are puting out questions that places more emphasis on language. Questions that will trip you up if you don't understand the nuances of the words used. It's tough enough having to apply the concepts taught without having to deal with abiguous interpretations of the questions.

[Alchemist]

Hi - I found an alarmingly large no of discrepancies between this answer list and my son's solutions. Would appreciate all assistance provided for these next few posts. http://i55.tinypic.com/291jf3d.jpg\">