This is to inform you that Sports Day is going to be held on Wednesday, December 20th, 2006. All children should come to school dressed in white t-shirts, white trousers and green caps. On the 16th, 17th, and 18th of December the children will be in school to practice for their Sports Day activities.
This is just my opinion of how I would correct your writing. Other teachers will have slightly different corrections.
Student or Learner