Colors

The thing to keep in mind when working with toddlers or two year olds is variety and repetition!
When learning to become a teacher, you learn that each child has a different learning style.  Spatial, auditory, linguistic, kinesthetic, mathematical, interpersonal, and intrapersonal. 

• Spatial: visual; using pictures, images, etc.
• Auditory: aural; using sound and music
• Linguistic: verbal; using words-speech and/or written
• Kinesthetic: physical; using body, hands, sense of touch
• Mathematical: logical; using logic, reasoning, and systems
• Interpersonal: social; learning best in groups or with other people
• Intrapersonal: solitary; learning best alone and self studying

That is why it is very important when working with any child to use a variety of methods, techniques, and mediums to teach and review curriculum.
When working with my first son and teaching him his colors, we used a variety of resources.  We read the typical baby books that have one color per page and several items per page of that color.  We also worked with a peg puzzle he has and reinforced shapes and colors every time he played with it.  But it doesn't stop there.  We reinforced every where all throughout the day. 

Other ways to practice colors are through crafts, like coloring with crayons, markers, or colored pencils, painting, or playing with play dough.  Just make sure to reinforce color names while you're doing it.  You say the color, then have them say it.  As they gain confidence, have them say the color they are using, or make it a little game and say a color and have them find it.

Another thing to consider is teaching another language.