Grade 10 science- confused on isotopes!?

The parent isotope decays to daughter isotopes. For example, C-14 decays through C-13 to C-12 with a half-life of about 5730 years. C-14 is the parent isotope, and C-13 and C-14 are the daughter isotopes (although you won't find any C-13 around; it's totally unstable).