Sound like a lazy native: Weak vowels.

Here is a list of words that have weak forms 

(You can hear me - Seonaid - say the examples by clicking the arrow. Remember, this is me speaking quickly and not being careful. This is how I talk with English-speaking friends.)

http://www.perfect-english-grammar.com/english-listening.html

Your homework on February 9th is to dedicate 10 minutes to pracitising your pronunciation by copying Seonaid's. 

First, listen and repeat 5 phrases. 

Then, one by one, pronounce the same phrases again and check Seonaid's pronunciation. 

Now, close your eyes, and try the phrase again. With practice you'll find it easier.

On Wednesday, show the class how lazy you can be.