Instruction in arithmetic throughout the Lower School emphasizes computation and reasoning. We use the American abacus, the “Numberaid,” to familiarize the student with the decimal numeration system. We give particular attention to the structure and mechanics of addition, subtraction, multiplication, and division.
All St. Thomas’ students must memorize all addition, subtraction, multiplication, and related division facts by the end of the second grade year. By the end of the third grade our students have become proficient in all four arithmetic functions using whole numbers.
Arithmetic instruction in the Lower School also includes the study of time, calendars, weights and measures, money, fractions, and descriptive geometry. Additionally, extensive drill in the solution of word problems provides ample opportunity for the development of mathematical concepts and reasoning.