Spellings - adding the suffix 'sion'.
If the root word ends in 'd', remove the d and add 'sion'
If the root word ends in 'se', remove the 'se' and add 'sion'
If the root word ends in 'de', remove the 'de' and add 'sion'.
I have also set you an assignment on Spelling Shed so you can practise this week's words.