I was taught algebra in school (only in a manner of speaking because I could fathom little of it) and later found zero application for it in my life. The same goes for the geometry theorems I had to do and the chemistry symbols I had to try (and failed) to mug up. So clearly I spent a lot of time in school learning things that were useless to me later in life. Now how could my time have been better utilised in school? Perhaps some understanding about the practical world and things would have made much more sense.
Simple manners

Say ‘Thank You’ and ‘Please’ even when you’ve paid for a service. Don’t hesitate to say sorry. Smile. Listen. Make eye contact (this is a big one). Simple manners that make a human being so much nicer to be around.
Training for community living

Kids should be taught basic traffic and road use rules, the importance of them being not littering, and taking care of public property. Instill the idea that common property is as important to take care of keep clean as our own.
Some volunteer work

All kids ought to be involved in some charitable work or community project. Helping out at an orphanage for instance would help develop some empathy for the less privileged and don’t take their own privileges for granted. Cleaning the neighbourhood could really drive home the point of taking care of public property and not littering.
Developing the critical faculty

Our schools place so much emphasis on rote learning that kids are never required or even allowed to question what they learn. Debate, curiosity, probing deeper and examining a subject critically is vital for mental growth but lamentably absent in our school system.
Developing communication skills

In a world where kids are constantly online, messaging, texting and ‘Facebooking’, the simple art of conversation got lost somewhere. Effective communication skills to get across a view without anger or acrimony and the ability to listen respectfully and non-judgmentally are vital.
Basic cooking/sewing a button (for boys)

At some point, girls are taught basic household chores or they have to figure these out on their own. However, the same is not true for boys. Boys have to be taught that there is no ‘woman’s job’… not only are these useful life skills; this is also helps in sensitizing boys about gender equality.
A mandatory aptitude test

This is probably more for ambitious parents than their kids. An aptitude test can help to find out what a child is good at and is likely to be successful at. This prevents a child being pushed willy nilly into jobs considered ‘safe’, or ‘lucrative’ or ‘worthwhile’.
Changing a fuse

Boys and girls both have to be able to change a fuse, change a car tyre, mend something that is broken… all valuable skills to create a self reliant human being.
First aid

Kids should know how to react if there is an accident, someone breaks a bone, hits their head… in practice not out of a book with poor illustrations.
Time management

Apart from telling kids how to finish an exam paper on time, there is little of this being taught in our schools. The importance of being punctual, of not making people wait, the futility of procrastination and the importance of prioritization could benefit all kids.