An insulated shipping container is provided for maintaining a substantially uniform internal temperature. The base, walls and lid of an outer box define an enclosure. An insulating body and an insulating cover are located within the enclosure and define an insulated cavity. A chamber having a plurality of chamber sides is configured to hold one or more payloads at the substantially uniform internal temperature. A temperature control material distribution structure is located within the insulated cavity for constraining motion of temperature control material units. The temperature control material distribution structure comprises at least one partitioned tray or trough. The at least one partitioned tray comprises a tray bottom; and a plurality of partition walls extending away from the tray bottom and defining a plurality of partition compartments.