Would Emerson's ideas about education be supported in elementary schools today? Why or why not? He believed children should be given the choice of what to study and what to learn. They should be exposed to many kinds of learning, but then they should choose what suits them best.

While Emerson would be pleased at elementary education's advancement, he would say there is more to do to create a system of formal elementary instruction that maximizes student choice.
Emerson was passionate about students having choices in their studies. Emerson saw the educational setting based on rote instruction as failing to ignite student passion: "It is ominous, a presumption of crime, that this word Education has so cold, so hopeless a sound. A treatise on education, a convention for education, a lecture, a system, affects us with slight paralysis and a certain yawning of the jaws." Emerson believed that the "certain yawning of the jaws" was because those in positions of power did not construct education with the student voice in mind. Emerson believed education "should be as broad as man" and should enhance "elements in him." He believed education should be geared towards individual passion:

The imagination must be addressed. Why always coast on the surface and never open the interior of nature, not by science, which is surface still, but by poetry? Is not the Vast an element of the mind? Yet what teaching, what book of this day appeals to the Vast?

Emerson felt the student experience was the most important element in education. He felt this was lacking in the educational system he saw around him.
In today's education system, there are more choices for students. In many elementary schools, delivering science and engineering instruction to as many students as possible is prioritized. There are more arts, physical education, and music classes offered to students than in Emerson's time. These opportunities broaden students' choices of future paths. With the increase of responses to intervention, elementary schools do a better job of tailor-making educational plans to fit the needs of every student. Teachers at the elementary level embrace learning centers, inquiry-based learning techniques, and self-selected writing and reading. They also do more in terms of encouraging student voice in the process of education. Elementary education embraces a deeper understanding of how facts fit together in constructing knowledge. This moves away from how Emerson saw education "coast on the surface." Additionally, Emerson would be happy with how there is more access to education than ever before. More young people are being educated than in Emerson's time.
I do think there are elements in current elementary education Emerson would find disturbing. The reliance on data-driven analysis in the form of standardized testing would concern him. He yearned for education to encourage a "vast" element of the mind, and as a result would recoil at the emphasis placed on standardized testing. When children in first or second grade have to experience the pressures of a high-stakes standardized assessment, instruction loses its appeal to the "vast." Rather, it gears itself toward success on the test. Emerson would repudiate elementary schools cutting back on "non-essential" courses like art, music, and physical education in favor of more instruction on testing content. Schools that do this embrace Emerson's belief of the "hopeless" condition of education. When standardized testing is given importance over all else in elementary education, student choice and voice diminish. Emerson would criticize this limitation. This is not to say he would reject modern elementary education, but he would say the steps taken to enhance a child's imagination should continue and the movement towards over-reliance on testing data should recede.
https://archive.vcu.edu/english/engweb/transcendentalism/authors/emerson/essays/education.html