English grammar features both a simple and a continuous tense. For present simple, the base verb does not change except in the third person, when it takes an "s" ending: He skates. The present simple refers to activities that you do regularly and may be used with adverbs of frequency such as "often." The present continuous, also called the progressive, refers to activities you are doing at the moment of speaking: He is playing tennis [right now implied]. Present continuous takes a verb phrase that includes the correct form of "to be" plus the base verb with the "ing" suffix. The present continuous also indicates an appointment when used with a time: He is skating with friends at 3:00 today. (All Reference 1)
Teachers use grammar instruction to facilitate educated communication. (Reference 2) Therefore, teaching grammar in the context of communication promotes better retention of the target structure. (Reference 3) Start by teaching the present simple and present continuous separately, one for habitual activities and the other for current actions. When students master each separately, teach their differences explicitly. Present the rules both orally and in written form to facilitate different learning styles. Utilize many examples and non-examples, or phrases that could be mistaken for examples, such as "ing" nouns. Prepare them ahead of time to ensure a steady supply when needed. (See Reference 2, Goals and Techniques)
Students need plenty of practice to cement their new learning. Guide them in their practice by provided sentences in which only the verb is missing; students fill in the blanks with the correct forms. Grammar books and websites provide numerous such worksheets. (Reference 1) Lead them in a communicative activity in which they are repeatedly having to choose between the two tenses. This can be in the form of a partner or group activity during which they ask and answer questions using the simple or continuous tense as appropriate. (Reference 2, Grammar activities) Have students play with the two tenses such as in a game of charades: one student mimes an activity, the others describe it using both tenses. (Resource 1)
Traditional tests or quizzes are one method of assessment. Create a quiz around the usage of the two structures, using questions that mirror the way students learned to use them in class. However, more authentic assessment involves developing communicative activities during which students can demonstrate their comprehension. Again, recreate the ways students studied the simple and continuous tenses. Develop a rubric to record your evaluation of their accurate usage of the two tenses. (Reference 2, Assessing) Getting students to write, though, using the target structures is one of the most effective methods for evaluating their understanding. Make the writing assignment as authentic as possible. (Reference 3) For example, have students write a description of a picture or a postcard during an imagined vacation. Explain ahead of time how many of the target structures you want to see. (Resource 1)