They can then use this checklist every time they write something. The more the students read, the more it is likely to help their spelling. After the students have read a text, you could ask them to go back and focus on the words. Discuss with the group their choices and find out why they chose those words. Then ask them, individually or in teams, to find as many examples as possible of those letter patterns in the text.
Students can test each other in groups.
On one side of some cards, write words which students know but may find difficult. Make sure there are at least three examples of each of the letter patterns. Shuffle the cards. Each student has 10 or so cards. Students take it in turns to put one of their cards in the centre of the table and say the word on the card at the same time.