One hundred flash cards, eight to a sheet, for the subtraction facts within 20: each takes 1 to 10 away and leaves 1 to 10, from 2 − 1 to 20 − 10, so every card is the partner of an addition fact to 10 + 10. Each front shows a fact stacked as in a column; its back shows the difference, with the fact printed small in the corner for sorting. Print the pack double-sided and flip on the long edge: each back sheet is laid out mirrored, so every card's back lands behind its front. On a printer that prints one side, choose Fronts only under Print, put the printed sheets back in the paper tray, then choose Backs only. Fronts have a thick frame and backs a thin one, so a card turned the wrong way stands out.
Show a card and ask for the answer and the addition fact behind it: 15 − 8 = 7 because 8 + 7 = 15. Partners take turns showing and answering, turning each card over to check. Work through part of the set at a time and keep a practice pile of the facts a child misses.
Five minutes a day goes further than an hour once a week. Start with the facts your child knows, then add two or three new ones each day.
This pack supports the following Common Core State Standards for Mathematics:
© Copyright 2010. National Governors Association Center for Best Practices and Council of Chief State School Officers. All rights reserved.
Flash cards for the subtraction facts within 20, from 2 − 1 to 20 − 10, with the fact on the front and its difference on the back. Children say each answer, then turn the card over to check.
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