It is necessary to send our kids to playschool?

Not necessarily. If you have the time and the ability to teach your child what they would learn in playschool, you can let them stay home. 

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not bad idea it is

Not necessarily. If you have the time and the ability to teach your child what they would learn in playschool, you can let them stay home. 

Yes’m, it sure is.

What is playschool?  Kids can go outside and play.

It's not necessary at all.

In most countries it is not legally required. You might think that going to playschool or pre-school would give your children social advantages and possibly educational advantages, but the choice is yours. 

Do I get the impression that you feel a sort of societal pressure to send your children to playschool?

Playschool? Do you mean "preschool"? Yes, it is pretty much necessary to send your child to a year of preschool before kindergarten. They need the preparation, both in how to behave in school and in the preliminaries to kindergarten. Kids in kindergarten now are expected to already know the alphabet and to be ready for simple math. There are lots of studies showing that children who go to preschool do better academically than those who don't. 

I think so, it helps them socialise with other kids, you can see the difference when they start school.