Begin the lesson with a prepared lecture. As your class is between the ages of 6 and 12, keep your lecture fun and friendly. Include basic information about why we have seasons and the mechanisms of seasonal changes. Focus your lesson on how seasonal changes affect trees. Create an interactive lesson where you ask students for input. For example, ask your class when leaves change and ask whether anyone knows why it happens. Encourage and answer your stduents' questions.
Incorporate visual aids into your lecture. Use a slideshow presentation, show video clips or even just put up pictures as you go through your lecture. Tailor your information and visual aids for the age of your students. Younger students benefit from simpler information and more child-friendly pictures and videos. Older students can learn more complex information and real-life visual aids.
After the lecture, have students participate in an activity related to seasonal changes in trees. For first and second graders, photocopy pictures from a coloring book of trees in all four seasons. Have your students color in the trees according to season. For any elementary-age group, have students divide a piece of paper into four sections and ask them to draw a tree as it looks in each season. For a more longitudinal activity, take students outside to observe live trees. If possible, adopt a tree near your classroom and take your students out at least once per season to observe seasonal changes. During each visit, ask students what is going on inside and outside the tree to produce these visible changes.
Once the activity is complete, bring students together as a group to summarize the lesson. Go over the main points of your lecture briefly to remind your students of the lesson's most important aspects. Alternately, bring students together and ask questions about specific aspects of seasonal changes in trees to see how much information they've retained from your lesson plan.