Science has indeed help us to make our lives more easier and convenient in may ways,like e.g communication...(Then,perharps you can talk about this topic.) 

We communicate with ppl in many ways like by emailing,faxing,calling,smsing,letter-se... and more.Lets talk abt one topic first. 

Emailing.It's a kind of mail when you can send thru computers 
.there are different advantages using this communication way,like you are able to change the fonts' colours,you do not nid to go to the postbox to post your letter,you are able to send large powerpoints and documents thru email,you are able to save paper too.there are also disadvantages using this communication way,like you are not able to have second thoughts after you've sent an email,there maybe viruses when you receive a mail,you do not know who is the sender if someone send you an email. 

Okay,i guess this is a long speech for you to present :) 

Best of luck to you :)
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