Catherine Stern
Catherine Brieger Stern ((1894–1973) was a German psychologist and educator. Born under the name Käthe Brieger, she developed sets of mathematical manipulatives similar to Cuisenaire rods for children to use in building up their number sense and knowledge of arithmetic. Her book, "Children Discover Arithmetic" (1949) was used by others to work on the problems that children face when learning arithmetic. In 1938, she emigrated to the United States. From 1940 to 1943, she was a research assistant to Max Wertheimer at the New School for Social Research.