英语作文通知的开头可以根据不同的场合和形式有所不同，但一般应包括以下几个要素：
标题
标题通常用“NOTICE”字样，每个字母大写，居中显示。
发文单位
发文单位名称可以写在标题上方或正文的右下角。
正文开头
正文的开头应简洁明了地交代通知的事项，包括何事（what）、何地（where）、何时（when）、何人（who）。
称呼语
如果是口头通知，通常会有称呼语，如“Ladies and gentlemen, may I have your attention, please？”。
结束语
口头通知的结束语可以是“That’s all. Thank you.”。
示例
书面通知开头示例：
```
NOTICE
We are pleased to announce that the English Speaking Contest will be held on October 30th at 7:00 pm in the school auditorium.
All Grade 12 students are required to participate. Please sign up at the Student Union office before October 20th.
We look forward to your active participation.
Student Union
```
口头通知开头示例：
```
Ladies and gentlemen, may I have your attention, please? I have an announcement to make. The English Speaking Contest is scheduled for October 30th at 7:00 pm in the school auditorium. All Grade 12 students are required to participate. Please sign up at the Student Union office before October 20th. We look forward to your active participation. Thank you.
```
通过以上结构和示例，可以有效地撰写出清晰、简洁且符合规范的通知开头。