Select a set of colored materials, such as blocks or small animal toys. Choose materials that are simple, without a lot of irrelevant information (such as differing textures or shapes) because these may distract the child from the color. A dollar store, or an education supply store that sells manipulatives and counters for math instruction may have sets of these items.
Sit near the child and gain his attention. Comment on the color of the object you have, saying something like, "Look at this blue block. Do you want the blue one?" Encourage the child to make a choice by pointing at the object or saying "blue." Allow the child to play with the object briefly. Repeat with objects in two or three different colors, but do not try to introduce all the colors in one play session.
Offer the child a choice, once he consistently repeats color names or points to items as you show them. Say, "Would you like the blue cup or the red cup?" If the child makes an error, pointing to the blue one while saying "red," say, "I'm confused, do you want the red cup or the blue cup?" Hold out or point to the cup you are naming. Give the child a chance to correct his choice.
Read picture books with the child that include simple pictures. Even if the book is not about colors, you can ask the child "What color is this?" about any picture on the page. Remember to give lots of verbal praise for correct answers, and to model the correct answer if the child makes a mistake. You can say, "That duck is yellow," to give the right answer without drawing a lot of attention to the error.
Incorporate color naming into many activities throughout the school day, including drawing and coloring, game play and choice making in any setting. Encourage parents to offer choices to the child when picking out clothes. You also can create color matching games that require children to match toys to same-colored containers.
Expand on the child's utterances when he comments on an object. If he says, "A truck!" you can reply, "I see the blue truck!" This will encourage the child to use the color words to describe objects in a meaningful way. You also can ask him, "Which truck?" to encourage the use of color words to describe it.