Many of my students confuse singular and plural forms of 3rd person present tense verbs. This activity presents sentences in direct contrast. Each sentence pair uses the same activity, but one sentence targets a singular subject and the other targets a plural subject.
I would start out by presenting 2-3 models myself and then allow the students to engage in sentence completion. At first, you may need to give them the two choices. (ex. sleep, sleeps) and let them choose which to put in each sentence. As they become more independent, you can even remove the sentence itself, having them formulate a sentence on their own. After practicing with sentence pairs in direct contrast, present the pictures or sentences in random order to further generalization of the task.