Unit 1b

1MA.A.2 solve real-life addition and subtraction problems within 20; explain the relationship between addition and subtraction and apply the properties of operations (1.NR.2)

• 2.a solve addition and subtraction problems within 20 using a variety of strategies (1.NR.2.1)

• 2.e use the meaning of the equal sign to determine whether equations involving addition and subtraction are true or false (1.NR.2.5)

1MA.E.6 use appropriate tools to measure, order, and compare intervals of length and time, as well as denominations of money to solve real-life, mathematical problems and analyze graphical displays of data to answer relevant questions (1.MDR.6)

• 6.d ask questions and answer them based on gathered information, observations, and appropriate graphical displays to compare and order whole numbers (e.g., picture graphs, bar graphs with up to 3 categories) (1.MDR.6.4)

Students are provided with learning experiences to develop strategies such as: 

• Counting All: 5 + 2 = . The student counts five counters. The student adds two more. The student counts 1, 2, 3, 4, 5, 6, 7 to get the answer. 

• Counting Back:  12 – 3 = . The student counts twelve counters. The student removes a counter and says 11, removes another counter and says 10, and removes a third counter and says 9. The student knows the answer is 9 since they counted back 3. 

• Counting On

• Making Ten  

• Adding Up in Chunks

• Decomposing a number leading to a ten  

• Using the relationship between addition and subtraction within 20 (knowing that 8 + 4 = 12, one knows 12 – 8 = 4); and creating equivalent but easier or known sums (6 + 7 is the same as 6 + 6 + 1 = 12 + 1 = 13).