I think the Common Core curriculum lays it out very well, the 'null hypothesis' is introduced in 6th grade and Baysean methods are discussed in High School:
Kindergarten: Classify objects into given categories; count the numbers of objects in each category and sort the categories by count.
1st grade: Organize, represent, and interpret data with up to three categories; ask and answer questions about the total number of data points, how many in each category, and how many more or less are in one category than in another.
6th grade: Recognize a statistical question as one that anticipates variability in the data related to the question and accounts for it in the answers. Understand that a set of data collected to answer a statistical question has a distribution which can be described by its center, spread, and overall shape. Recognize that a measure of center for a numerical data set summarizes all of its values with a single number, while a measure of variation describes how its values vary with a single number. Summarize and describe distributions.
7th grade: Use random sampling to draw inferences about a population. Draw informal comparative inferences about two populations. Investigate chance processes and develop, use, and evaluate probability models.
8th grade:Investigate patterns of association in bivariate data.
High School: Summarize, represent, and interpret data on a single count or measurement variable. Summarize, represent, and interpret data on two categorical and quantitative variables Interpret linear models. Understand and evaluate random processes underlying statistical experiments. Make inferences and justify conclusions from sample surveys, experiments, and observational studies. Understand independence and conditional probability and use them to interpret data. Use the rules of probability to compute probabilities of compound events. Calculate expected values and use them to solve problems Use probability to evaluate outcomes of decisions.