The natural sex ratio at birth is close to 50:50

Oliver was a runner when he was younger, winning many race awards on the amateur circuit. Arthritis in his knees forced him to give up running, so he learned to use a recumbent bike that he could propel by pedaling with his arms. This enables him to keep participating in the amateur athletic community. Which of the following features of the life-span perspective describes Oliver's experience?

a. multiple causation b. plasticity c. historical context d. multidirectionality

Initially, Tawilla's teacher would carefully guide her through tasks in her third grade class, at times going so far as to physically guide her

However, over time as Tawilla's performance and understanding had improved, her teacher gradually withdrew her assistance. According to Vygotsky, this kind of help is referred to as __________ a) private speech. b) a zone of proximal development. c) a zone of potential development. d) scaffolding.