Another way to convince your supervisor to sponsor your convention attendance is to write him/her a letter. Below is a letter template that you can use to explain to your supervisor why he/she should sponsor your convention attendance. Please feel free to adapt it in any way that you want.
Letter to Supervisor
< Date >
Dear < supervisor’s name >,
I would like to attend the 2016 TESOL International Convention & English Language Expo, the largest convention focused exclusively on English language teaching for speakers of other languages. The convention will be held 5-8 April 2016, in Baltimore, Maryland, USA. This is the most important meeting for English language teaching professionals worldwide, and it draws more than 6,500 attendees every year. I am seeking sponsorship for the registration fee, travel expenses to the convention, and living expenses during the convention. A detailed cost breakdown is included below. I believe this is a wise investment.
The TESOL Convention offers a number of education sessions that are directly applicable to my work, and most offer Continuing Education Units. The convention will also enable me to network with a variety of experts and colleagues from around the world. The presentations are tailored to English language teaching professionals and provide information on how to <list benefits to your responsibilities>
After reviewing the convention brochure, I have identified numerous education sessions that will help me gain knowledge and understanding about how we can improve. The presentations are facilitated by fellow English language teachers and researchers who have faced similar challenges. Each of the presentations listed below is directly related to an issue we currently face. Getting the information in a seminar format will enable me to share the information with my colleagues at, <institution name> thereby improving the work we all do. (Incidentally, I have listed only a few of the relevant seminars. Including them all would make this memo much too long.)
The full price convention fee is $585 <insert member price here if relevant> if I register by 22 January 2016, but if I join TESOL when I register, I can save $240.
Here is the breakdown of convention costs:
Roundtrip Airfare: <$xxxx>
Conference Fee: <$xxxx>
Total costs: <$xxxx>. <If you have found ways to save money, you should enter them here>
As you can see, my attendance at the 2016 TESOL International Convention & English Language Expo is a wise investment that will yield rich dividends for < name of your organization >. I look forward to discussing the convention with you at you convenience.
< your name here >