This activity is called Good Deeds Bracelets for Lent and it comes to us from Arma Dei. They describe it this way:
Inspired by St. Therese, this bracelet works similar to other good deed bead bracelets, as the beads slide and stay in place, recording each good deed, extra prayer (foregone opportunity to complain) or sacrifice.
Arma Dei sells a craft kit that contains everything you need to create these bracelets. Be sure to take a look.