Originally Posted by Scheherazade
I am afraid I find this part of your plan a little ambitious. If you don't mind, I will suggest some changes in your Graveyard plan. Why don't you take the poster to the class with blank tombstones in the beginning of the term? Ask your students to write an essay on a subject you choose (or maybe give them two options to choose from?) without giving them a list of errors or scoring system. Once your students complete their initial assignment, you can make a list of the most common mistakes they make. For example:
1. Proper use of capital letters.
2. Full stop
3. Subject-verb agreement
4. Commas
5. Choosing the correct tense
6. Adjectives
7. Adverbs.
Then maybe you can introduce a 15 minutes 'Grammar' session every week and concentrate on one of these point. Once you covered the point and have done some exercises on them, you can 'bury' the mistake and put them up on your poster.
Your students might be daunted by a long list of these mistakes if they are confronted by them as soon as the term starts and especially if they are expected to overcome them on their own (like assignment task you suggest and the scoring rubic - I am not sure how they would take it if you start the year by saying 'I expect you will make these mistakes and if you do, you will be 'punished'). It is always a good idea to show the students the correct usage before asking them to correct their mistakes.
I know concentrating on one mistake a week sounds like a painfully slow process. However, considering that these are probably life-time habits for them, it is better to move on slowly -only after making sure that they have mastered one point. This way, the new and correct forms they have learnt are more like to be remembered.
At the end of the term/year, you can return their initial assignments and maybe ask them to rewrite them with their new grammatical knowledge and correcting their own mistakes. It is always fun to realise what a long way one has come! :)