Allow the child to 'share the marker' and write some of the letters and/or words.
Gather several single colored objects such as a red ball, a green grape, or a yellow lemon. Pick up one object and have the child say the name of the object and then the color of the object. Write the color word on an index card in that color marker. As you repeat this process with three or four colors, have the child place the objects in the row that has the color word index card above it.