Questionnaire
Personal Basic Information	Iterms		Options
	Gender		1	Male			◎
			2	Female			◎
	Age		1	21–22			◎
			2	20			◎
			3	19			◎
			4	18			◎
	Level of music education		1	Have not received specialized music education			◎
			2	Received basic music education (school music lessons, etc.)			◎
			3	Have received intermediate level music education (e.g., professional piano lessons, etc.)			◎
			4	Have received high-level music education (have received music competition certificates)			◎
	Number of children in the family		1	Three children or more			◎
			2	Two children			◎
			3	Olny child			◎
	Geographic location of the family		1	Urban			◎
			2	Suburban			◎
			3	Rural			◎
Category	Measurement items			1	2	3	4	5
Participation in group music activities (PGMA)	PGMA1	I actively participate in group music activities organized by the school.		◎	◎	◎	◎	◎
	PGMA2	I will practice and perform carefully in group music activities.		◎	◎	◎	◎	◎
	PGMA3	I will work with my classmates to ensure that the music activities go smoothly.		◎	◎	◎	◎	◎
	PGMA4	I feel that participating in group music activities enhances my musical skills and social skills.		◎	◎	◎	◎	◎
Positive social connections (PSC)	PSC1	I feel that I am part of a community of friends.		◎	◎	◎	◎	◎
	PSC2	I find connections with friends enjoyable and fulfilling.		◎	◎	◎	◎	◎
	PSC3	I feel accepted and understood when I interact with others.		◎	◎	◎	◎	◎
	PSC4	My friends make me feel valued and respected.		◎	◎	◎	◎	◎
Perceived peer support (PES)	PES1	My friends support me when I am in trouble.		◎	◎	◎	◎	◎
	PES2	I feel I have friends I can count on to share my worries and troubles.		◎	◎	◎	◎	◎
	PES3	I have friends who will offer help and advice when I need it.		◎	◎	◎	◎	◎
	PES4	I have friends who care about my feelings and needs.		◎	◎	◎	◎	◎
pro-social behavior (PB)	PB1	I will do my best to help those in trouble, even if I don’t know them.		◎	◎	◎	◎	◎
	PB2	I will try to cooperate if someone asks for my help.		◎	◎	◎	◎	◎
	PB3	I will feel sorry for someone’s misfortune and try to comfort them.		◎	◎	◎	◎	◎
	PB4	In an emergency, I will not hesitate to help.		◎	◎	◎	◎	◎
(1: Strongly disagree, 2: Disagree, 3: Neither agree nor Disagree, 4: Agree and 5: Strongly agree)