This is adapted from an answer to another question: 2,5 year old girl always picks black
Specifically, the linked source in that answer, Why Johnny Can't Name His Colors, mentions prenominal versus postnominal use of colors. This set me on track to this research article, Surprise in the Learning of Color Words (PDF).
The research suggests that using postnominal (or post-nominal) training is better for teaching children colors than prenominal training.
Results indicate that children as young as 2 years
begin to reliably master color words when hearing them in
training presented post-nominally, but not pre-nominally,
and that adults challenged with learning novel color
categories are affected by the same ordering effects. We
suggest that children’s difficulty with color word learning is
in part due to the challenge of having to make predictions
from words to the properties they refer to, rather than being
able to make predictions from the world to the words.
- Prenominal: "The red ball." The color comes before (pre) the noun (nominal)
- Postnominal: "The ball that is red." The color comes after (post) the noun (nominal)
Now, I don't mean to merely replicate @Bossykena's answer. I think the study I linked to provides better support for using postnominal training.
When I read the answer on the other question, we were having trouble getting my son to identify colors correctly. So, with the study in hand, my wife and I proceeded to use color descriptions almost exclusively in a postnominal fashion.
We saw immediate results. His grasp of colors and ability to identify similar objects correctly by their colors grew enormously in a short time. The largest results were in the first couple of weeks.
We would also go out of our way to include color descriptions when speaking to him. We were already doing that in a prenominal fashion, but without much success. This leads me to give credit solely to the postnominal training.
At the same time, we also tried to increase our use of American Sign Language when using colors. The ASL usage did not appear to have any real effect at that time, but we did not put a particular emphasis on the ASL at the time. Mainly, it was used to reinforce that the color words were the "key" words of the sentences. With our new child, we'll likely place a greater emphasis on ASL during color learning, mostly because our own confidence in ASL has grown.
Since we don't know for sure that the ASL helped, but it was a factor, I felt it worth mentioning. If nothing else, it may help you feel like you're doing more, which can be emotionally satisfying on its own.
- Use postnominal color descriptions: "The bucket that is yellow."
- Describe objects with colors more often (or parts of objects): "Go get your socks that have bottoms that are black."
- Try including ASL if you want more physical/active training