Students who know basic addition and subtraction facts with single-digit whole numbers are ready for extension facts using decimals in tenths. Handle the regrouping required (e.g., 0.4 + 0.9 = 1.30) by referring to the values (4 tenths plus 9 tenths equals 13 tenths), rather than by focusing on the placement of the decimal point. If students understand the values, they won’t have trouble getting the decimal marker in the right place.
Eight times facts can be revised using a “double double double” strategy. Dividing by 8 can use the reverse strategy: “halve, halve, halve”. Aim for speed and automaticity once students have memorized the facts.
