Cleft sentence

Hello, 

I am not sure whether the two sentences make sense in term of grammar and semantics.
Can you give me a hand with checking them
Thank you for your help.

1. It is parents who can spend more time on their children that improve children’s academic performance.

2. It is parents who can illuminate their children's mind that help them build a positive value system.

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May I make a suggestion, KK?

As part of your standard introductory form of posting a question to Forum commentators, you might want to consider this revision:

I am not sure whether .... make sense in term of grammar and semantics, and sound natural.

'Grammar and semantics' are only part of any language.  Sounding natural should also be of high interest to non-native speakers/writers.  The two sentences you ask about here may pass grammatically and semantically, but they are really not good examples of the natural sounding way of writing/speaking them.