Mathematics - Addition and Subtraction - Addition within 20 - Sums to 20 Drill

Show addition problems where both addends are 1-10 and sum is 11-20 (e.g., 7+8, 9+6, 5+9). 20 problems total. Show a ten-frame hint button if the student needs help. Timer per problem (optional, shows but doesn't penalize). Track which facts are mastered (correct in <5 seconds) vs need practice. At