Developmental Dyscalculia (DD) is a learning disorder affecting the ability to acquire school-level
arithmetic skills, affecting approximately 3-6% of individuals. Progress in understanding the root causes
of DD and how best to treat it have been impeded by lack of widespread research and variation in
characterizations of the disorder across studies. However, recent years have witnessed significant growth
in the field, and a growing body of behavioral and neuroimaging evidence now points to an underlying
deficit in the representation and processing of numerical magnitude information as a potential core
deficit in DD. An additional product of the recent progress in understanding DD is the resurgence of a
distinction between ‘primary’ and ‘secondary’ developmental dyscalculia. The first appears related to
impaired development of brain mechanisms for processing numerical magnitude information, while the
latter refers to mathematical deficits stemming from external factors such as poor teaching, low socioeconomic status, and behavioral attention problems or domain-general cognitive deficits. Increased
awareness of this distinction going forward, in combination with longitudinal empirical research, offers
great potential for deepening our understanding of the disorder and developing effective educational
interventions.

This collection of maps from MAPS ETC show demographic information for the United states ranging from 1700 to the early 20th century.

A map of the eastern United States in 1790 showing the western extent of the territories to the Mississippi, and the distribution of European–American population at the time. The map is keyed to show areas of population densities ranging from under 2 inhabitants per square mile to areas with 90 or more inhabitants per square mile.

This book is designed to introduce doctoral and graduate students to the process of scientific research in the social sciences, business, education, public health, and related disciplines. This book is based on my lecture materials developed over a decade of teaching the doctoral-level class on Research Methods at the University of South Florida. The target audience for this book includes Ph.D. and graduate students, junior researchers, and professors teaching courses on research methods, although senior researchers can also use this book as a handy and compact reference.

A map from 1912 of the United States, subtitled "Distribution of Population and Railways in 1900" showing the increase in population and expansion of the railroad network since 1850. The map is color–coded to show population densities ranging from areas with fewer than 2 inhabitants per square mile to areas of 90 or more inhabitants per square mile. Cities with populations over 8,000 are shown with circles proportionate to their populations at the time. The map shows the westward progression of the mean centers of population from 1790 to 1900.

Writing Commons is an encyclopedia for writers, speakers, and knowledge workers. Since 2008, we have published original articles on topics of interest to writers, speakers, and knowledge workers. Over 11 million students and teachers worldwide use Writing Commons for help with their college-level coursework in academic, workplace writing, STEM writing. Writing Commons serves as the required writing textbook for students in composition, professional and technical writing, workplace writing, business writing, fiction writing, and poetry writing courses. Beyond the classroom, Writing Commons is the go to source for professionals in workplace writing settings.