Should a woman change her cloths in front of a six year-old boy?

All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.

If changing clothes means being naked in front of a child, then it is not recommended, if he is aware of the meaning of nudeness and can distinguish it from the state of being clothed.

Allah Says (what means): {O you who believe! Let your slaves and slave-girls, and those among you who have not come to the age of puberty ask your permission (before they come to your presence).} [Quran 24:58]

The instructions of Allah, in the above verse, about children who have not reached the age of puberty to take permission before entering at the times when generally people will be in the state of uncovering, prove that being naked in front of those children who perceive the meaning of it is not recommended.

Imam Abu Is-haaq reported that he asked Al-Awzaa-‘i about the age of child who should ask permission, and the latter [Al-Awzaa-‘i] replied: “Four years.” [reported by Al-Qurtubi in his Tafseer]

Allah knows best.