I like this topic very much. However, it is very difficult to write. I think your essay is quite good, full of ideas, I 'd rate 4. But I think it's will be more interesting if you detailize a little. And also, I feel some places are not very correct in grammar. I make them italic
Generally, many people think that older people can learn nothing from young people. However , that is not always case. I hold the opinion that young people can help older people for many subjects such as (subjects) about new innovations, youth culture and new social trends.
To begin with, it is a fact that young people are better to use technology. Now, they have enough information about computer because children grow with computer. Thus,they can teach older people how to use computer and older people can use it to print their work or to sent (send) email. Besides this, altough ,today, mobile phone is an important communication tool, many older people have difficulties to use (in using it) . Young people can help them about using mobile phone.
Secondly, generally, older people do not (are not) familiar young culture. If young people help older people to learn their social activities, older people can have more enjoyable life. For instance, I helped (my ) grandfather how to use computer games and he enjoyed (it )very much.
Lastly, young people generally aware of new trends such as fashion , cinema or music. Children can help older people about clothing that everyone gets dressed or choosing cinema that everyone enjoys it. By this way, older people keep up with new trends.
So based on all mentioned points, young people can teach (older people ) many things that older people want to know, such as about new innovations,new trends and youth culture.