An (editable) PowerPoint document with 10 task cards for practicing sum and difference identities in Trigonometry. The ten cards are lettered A-J, with increasing complexity.
I printed out 4 cards per page, horizontally, then cut and laminated them into "decks" of cards. Students broke into groups of 4. Beginning with Card A, they worked the problem and then wrote their group's answer on the card with dry-erase marker. If they were correct, they could proceed to Card B. Most groups needed 45-60 minutes to complete all 10 cards. No calculators were allowed. It was great practice!!!!
(Thumbnails here look bad but the cards are actually really cute!)