Educators across Boston are noting a shift in the emphasis of the curriculum they’re expected to teach as more schools introduce science, technology, engineering, and math – the so-called STEM subjects – to newly reading preschool students. Preschools have long followed the practice of elementary education and dabbled with bits and pieces of science-based teaching in their everyday learning: Playing with blocks, for example, learning numbers, and coloring are all aspects of engineering, math, and science, writes Michael B. Farrell at the Boston Globe. “But what is happening now is that such lessons are becoming formalized within a preschool curriculum. And within the early childhood development community there is a greater emphasis on training teachers to turn simple play into lessons that encourage critical thinking.” This comes as many education experts, policy makers, and politicians note a sea change in the importance of STEM subjects and the way we teach them, pushing for a greater focus on science, technology, engineering, and math. The percent of college graduates with science and engineering degrees has declined over the past 45 years, provoking many organizations to promote STEM subjects through competitions and awards as a way to stimulate interest and boost the number of scientists, computer programmers, engineers, and mathematicians coming out of American universities. “The Organization for Economic Cooperation and Development ranks the US 24th among 31 of its member countries in terms of employed 25- to 34-year-olds with degrees in science, math, or related fields.” However, as part of President Obama’s budget plan for the next year, he is looking to invest to change these statistics. Obama has asked Congress for $80 million to train 100,000 math and science teachers in an effort to produce an estimated 1 million more college graduates with degrees in those subjects. These plans are nothing new for states like Massachusetts, who, since 2010, have been trying to improve science and math education from the preschool level through high school and encourage more college-bound students to pursue them as majors. Cathleen Finn, International Business Machines Corp.’s New England manager for corporate affairs, said: “The focus on STEM in early education is new, but it’s part of an effort to keep the focus on engineering so that we graduate more people in engineering. “That sets the stage for awareness as kids go through school.’’ However, some education experts who criticize the emphasis on work in the kindergarten classroom, saying that preschools need to strike the right balance between play and instruction. “And, many say, unstructured time on the playground is an important part of early education.”