Why is kids' stuff not equal to childrens' stuff?

[Andrei Romania]

Test No. incompl/inter-54 "Lots of Stuff", question 4

You shouldn't really have any difficulties with the work they're doing as it's very basic in fact you could call it ......... stuff.

(a) babies'
(b) children's
(c) kids'
(d) juniors'

Test No. incompl/inter-54 "Lots of Stuff", answer 4

You shouldn't really have any difficulties with the work they're doing as it's very basic in fact you could call it kids' stuff.

Correct answer: (c) kids'

Your answer was: incorrect
You shouldn't really have any difficulties with the work they're doing as it's very basic in fact you could call it babies' stuff.
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why is kids' stuff not equal to childrens' stuff

[Torsten]

Here the word kids is needed because it indicates that the questions or tasks are very easy.

TOEIC listening, photographs: Sale in the open air

[Jan]

Hi,
what is correct to write ?
kid's stuff or kids' stuff
children's stuff or childrens' stuff etc...
regards
Jan

[Conchita]

[Jan]

Hi Conchita,
nice to have a teacher like you , I think I have understood
thank's a lot
regards
Jan