Today have a look at all the -ment words on the following website. Pick one at a time, hide the word and have a go at spelling it.
Perhaps try these words first, which you can sound out and spell phonetically...
payment investment agreement amazement punishment
Sound them out and count how many phoneme/sound buttons you need to help you spell.
Can you clap the syllables too?
syllables - gov-ern-ment
phoneme/sound buttons - . . . _ . . . . .
g o v er n m e n t
. . . _ . . . . .