Why not write about some ways teachers have made a difference in your life? Your thesis could be something like: My teachers made me who I am today. Then you could explain how they encouraged you, taught you key skills or were there to listen. Think about how your teachers have made an impact, and share some personal anecdotes!
One wonderful teacher early in my teacher education made the observation that we all mold students--do we mold in a positive way or do we mold in a negative way. Write a note to a teacher who molded you in a positive way. Perhaps they made you feel accepted in a world of criticism. Perhaps they had a kind heart when you needed it. Perhaps they called you to task for not doing your best, and helped you realize that education is not an enemy. Simply share with that person how they molded you.
My best tip for essay writing is giving students mentor texts dealing with a topic similiar to the one chosen for them. For example, when we write expository essays, I give my students examples of an "A" paper, a "B" paper, and so on. It usually makes them feel more comfortable writing when they see that they are quite capable of a good paper themselves. Also, we do a great deal with modeling from mentor texts. When my kids have writer's block, I give them a line or a paragraph, and they can model their essay after that format. I hope that helps.
There is a very cute picture book called Thank You Mr. Falker. I read it to my classes each year and have them mimic the format of the book to write to a past teacher who has greatly influenced their lives. You can try reading it and see how it inspires you.
Another idea is to write an essay based on Walt Whitman's poem "There was a a Child Went Forth". Look up the poem, then immitate it with things your teachers have done for you. I do this activity with my Seniors every year.
Why not write on the "gift" that a passionate teacher offers to any students who will open their minds to new avenues of thinking? For instance, one student wrote in his journal that he was thankful to his teacher for the last discussion on "Brave New World" in which she showed the students through their responses that it was good to experience pain and sorrow, for without these experiences a person cannot be truly happy or human. The student concluded that he realized that without struggle a person cannot achieve the highest emotions. He/she would just be a "hatched" creation of some ordered world. (This life lesson was a gift from his teacher.)
The teacher was elated and edified by this student's entry.
Teachers love to know that they have made a difference in student's lives. They also like to be reminded that they have a noble profession. You could start out by talking about the different teachers you have had, and how they have helped you. That way, you can give the essay to more than one teacher. Use specific examples. It is better to talk about specific words or actions of teachers than discuss generally how a teacher "changed my life". Thank you for doing this, I'm sure your teacher will be thrilled to get an essay like this.
A great essay has the following components:
1) A great hook or attention getting statement.
2) background information
3) a great thesis
4) topic sentences that have an opinion
5) Support or evidence or substantiation in the form of facts, quotes, and references
6) Analysis of why your evidence is fir for the topic sentence
7) A conclusion that is not mere summary but a final purpose or significance of the work as a whole
8) A final dramatic statement.