Dear Jane, A good question that can not be answered without irony. Because we should admit that usually takes a long time in the cultural and humanities. Why? 1. One never knows whether a certain direction in the social sciences, which recently claimed to be telling the truth, is not being replaced by another direction that also believes that it is telling the truth. The process of historicization shows how strongly scientific truths of social sciences are relativized by history. 2. Assuming that the formal curriculum of education is represented by the public school textbooks, then the official procedure takes a very long time for a Ministry of Culture to give permission for a publisher to print a particular textbook in which scientists have collaborated , 3 So I want to answer the question. It takes a long time, too long. But there may be even more shortcomings in our educational system.

Understanding How Scientific Knowledge Is Constructed:-

• The research base on children’s understanding of how scientific knowledge is constructed is limited. Most studies have been conducted in laboratory settings and do not take into account instructional historyand children’s opportunity to learn about this aspect of science.
• Most children do not develop a sophisticated understanding of howscientific knowledge is constructed.
• Methods of science dominate the school science curriculum, with littleemphasis on the role of theory, explanation, or models.
• Children’s understanding of science appears to be amenable to instruction. However, more research is needed that provides insight into the experiences and conditions that facilitate their understanding of science as a way of knowing.

Dear Jane, A good question that can not be answered without irony. Because we should admit that usually takes a long time in the cultural and humanities. Why? 1. One never knows whether a certain direction in the social sciences, which recently claimed to be telling the truth, is not being replaced by another direction that also believes that it is telling the truth. The process of historicization shows how strongly scientific truths of social sciences are relativized by history. 2. Assuming that the formal curriculum of education is represented by the public school textbooks, then the official procedure takes a very long time for a Ministry of Culture to give permission for a publisher to print a particular textbook in which scientists have collaborated , 3 So I want to answer the question. It takes a long time, too long. But there may be even more shortcomings in our educational system.

15 years sounds too long. Take the plate tectonics theory. First introduced in the 1960's, explained more in the 1970's and 1980's, became part of the school curriculum after 2000, but it made the geology textbooks during the early years even though the details of the process were not known very well. If there are no major objections to a newer theory (like Snowball Earth) it may enter texts after a couple of years, but it may not go into schools for 15 years yet.

On the other hand, if you take a more controversial topic like flying saucers there will be no word for 50 years or more although popular knowledge and Hollywood have already "explained" the subject to almost everybody young and old.

In my experience, the length it takes for up -to -date scientific knowledge to enter the formal educational curriculum depends on the context and the readiness of the political framework in a given country to facilitate the creation, diffusion and integration of new knowledge in the formal curriculum.

I followed this subject long time ago when I taught a university-elective course under the name of (Chemistry & Society). The major reference for that course was the "1980" textbook:

Chemistry, Man, and Society by Jones, Netterville, Johnston, and Wood.

The book discussed the idea of the time gap between a discovery & its application or marketing. The time gap varied for each case.

In the light of the above & in accordance with my observation in my long teaching service, we cannot set a figure or a number that will apply for the years required for the process of moving a new "proven" knowledge into the formal curriculum at schools.

Of course, a delay in updating is bad so there is a need for an educational system that employs active qualified professionals who follow up progresses at various fronts. I think that it is wise also to change the curriculum every 3-5 years since this will allow for updating.

I do not think that there can be a specific time frame. It all depends on the responsiveness of policy makers and the pro-activeness of the stakeholders.

There are a few things to consider, namely that nature of the scientific discipline you're referring to, and the knowledge in question. In the more applied sciences that do not require years of vetting of animal and human subjects research might find its way into textbooks sooner, especially if there is a need for the particular profession to have that knowledge disseminated as soon as possible. I think the "texts" used in grad school or even undergrad might have newer knowledge sooner that the K12 curriculum. It would behoove higher education to include more cutting edge knowledge sooner.