Must: start with capital letters and end in full stop, question marks or exclamation marks.
Should: include adjectives and
adverbs to add interest.
Could: include a connective.
There are a number of really good activities on BBC Bitesize KS2 which would help the children practise their spelling, punctuation and grammar skills.
Videos showing methods used in class are available on the children's abacus games pages. These show step by step methods of addition, subtraction, multiplication and division taught in class.