It might seem odd to think of pre-kindergarten toddlers as students in need of teachers, but the latest research suggests that some form of instruction may help children to better prepare for school. Nina Chien, a post doctoral researcher in pediatrics at the University of California San Diego found that children who were left to engage in free play in pre-kindergarten centers showed the least improvement in reading and math skills after one year compared with the children who benefited from some form of teacher instruction. The free play groups were provided with educational toys designed to stimulate their creative and cognitive processes, but they still learned up to two fewer alphabet letters and three fewer numbers than those who worked with teachers. Overall, when the children reached kindergarten, their teachers rated them up to 96% lower on language and literacy skills compared to their classmates. Chien based her study on 701 state-funded pre-kindergarten programs in 11 states, was surprised by the findings since more than 50% of children were enrolled in free-play based centers, an indication of their popularity. "It’s very popular to give kids rich educational materials, let them chose which ones they want to play with, and let them play, "she says. "It was surprising that this very popular model turned out not to be that beneficial. " The children who showed the most gains over the year in terms of learning the alphabet and numbers, as well as achieving basic reading and math skills, were those who had more individual interaction with teachers. Some teacher-based programs emphasized group instruction, while others involved more one-on-one guidance, in which teachers would encourage students to think more broadly or creatively. If a child drew a sun, for example, an instructor might ask how he could depict the brightness of sun, and guide the child to coming up with a way to draw the sun’s rays. Such encouragement, known as scaffolding, resulted in the most academic gains among the children. Based on her findings, Chien believes that there is still a role for free play, as the children in these programs exhibited greater creativity over the year. She also notes that the study involved public programs in which many of the students came from lower income households. Previous studies have shown that such children benefit more from individualized ins/ruction since they may not be receiving much guidance or support at home. But overall, she says, greater teacher interaction, combined with free play, might enhance children’s learning ability and better prepare them for school. Given the dwindling resources in public education, however, that may be harder and harder to achieve. It is indicated in Paragraphs 1 and 2 that ______.

A. free play in pre-kindergarten centers is essential to kids’ growth
B. the introduction of teachers’ instruction seemed inconvincible
C. free-play based centers are the main training form in pre-kindergartens
D. teachers’ assistance could enhance kids’ study abilities