Add a 1-digit number to a 2-digit number using known facts

ArithmeKit 26 provides a series of engaging exercises designed to help students add a single-digit number to a two-digit number using known facts. The tasks include adding the number 7 to a list of two-digit numbers such as 24, 54, 74, 34, and 64, and then repeating the process with a new set of numbers like 25, 55, 75, 35, and 65. Students are encouraged to observe patterns and apply their understanding to additional sums. The exercises prompt learners to explore different strategies and notice the consistent outcomes when adding the same digit to various numbers. For example, they might find that adding 7 to numbers ending in 4 always results in a number ending in 1.

Further activities challenge students to solve problems with missing digits, ensuring that the sums are correct. For instance, they must find which digit, when added to 6, equals 4, or what digit plus 1 equals the same as 1 plus another digit. The resource suggests a strategy proposed by a character named Coco, which involves breaking down the number 7 into 5 and 2 for easier addition. Students are invited to create their own problems and to convince themselves and others of the correctness of certain sums, like 38 + 6 equals 44 or 57 + 8 equals 65. The materials encourage the use of known facts to verify the accuracy of these calculations. This interactive approach to learning arithmetic is designed to deepen students' understanding and fluency in addition.