For this lesson using examples of imagery, you will need a class set of the poem, several sheets of plain white paper, and coloring supplies. You will also need to divide your class into small groups; I'd say 3 or 4 students at the most per group is a good round number.
I like to start by reading the poem out loud to the students first. This way they get a chance to hear it read out loud by a good reader, and it gives them a basic picture of the poem in all its glory.
The next step is to assign each student group one section of the poem. How you divide the poem is up to you, but make sure there's some vivid imagery in each section. In an average-sized class, each group will get two or three stanzas of the poem to work with. Tell the group members that their task is to identify the imagery in their section and represent it visually on paper. Then they need to explain the significance of that imagery in a mini presentation to the rest of the class.
This poetry lesson plan allows students to take a difficult poem and break it down into easily digestible parts in small group work. Then by explaining their section of the poem to the class, they have to really dig into that small section and the rest of the class benefits from the explanation. The examples of imagery help them to visualize the poem and appreciate Eliot's craft.