There are a few things you can do. An old favorite is playing "Hangman"- draw underline dashes on a whiteboard (six for "apple", eight for "dinosaur" etc) and have students take turns guessing what fills in the blank. Every time they get it wrong, mark the letter in a "Guessed" box and then draw one more line of the hangman, or, if you're worried the hangman will be an upsetting image, draw something else, like a cat or whatever. The point is just to get them spelling.
You could also do a spelling bee. Have students pair off with words on flashcards or pieces of paper and ask each other in English "How do you spell ____?" and the children must answer verbally. You could up the anty by having the children make their own "spelling lists" for their opponent... up to five words from their textbook or homework that they then ask the other to spell. If you have a really shy class, have every kid write one word on a piece of paper and then put it in a basket or hat and you can ask each student, one by one, to spell a random word that was submitted.
Hope that helps!
