Why Did My Friend Say It Isn’t Wasteful to Use Last Year’s School Supplies?

(Questions from a little sister)

We were travelling just before school started. My dad told me, “Mahya, there’s no time. By the time we get there, it’ll be too late to buy you school supplies, a bag, and so on.” I said, “Dad, I already have a bag and supplies.” Several times this year, a friend in my class has asked me, “Mahya, why are you using last year’s bag and pencil case? Didn’t you get new ones this year?” I told her, “I saw that my things were still in good shape, and I didn’t want to be wasteful, because wastefulness is bad and God does not love those who are wasteful.” She laughed at what I said and asked, “What waste?” Teacher, isn’t wastefulness bad?