# Decomposing to Subtract from a 10 (When Subtracting within 20)

Tonight’s homework is understanding HOW to decompose or break apart numbers in subtraction. Monday we go into more difficult equations, so it is important that we get a good foundation of this concept now. Just a heads up: students are not required to use number bonds on tonight’s homework, but they will be doing this on Monday.

The homework is divided into three sections: solving simple subtraction problems, write the missing addends, and a couple story problems.

The first section asks you to circle the number sentence if you must subtract from the 10. We learned in class that you need to subtract from either the ones or the tens. For example, in the equation 14-3, I need to either subtract from the ones or the tens. If I can subtract 3 from 4 (which I can), then I don’t need to worry about taking any from the ten. But if my equation is 13-6, and I can’t take 6 away from the number in the ones place (3), then I have to take it away from the 10. If I have to take away from the ten, please circle the number sentence. Feel free to use other subtraction strategies such as a number line, touch dots, or mental math to help find the answer- kiddos just need to know if they can subtract the ones without breaking apart a 10.

The second section of the homework asks the students to fill in the blank to make the number sentence correct. Students will need to use addition strategies to solve the first side of the equation, and then try and figure out the number that is missing that will make the equation balance out.

The third section of the homework is story problems. I would like students to use the RDW method to solve these problems. RDW stands for READ, DRAW & LABEL, and WRITE the NUMBER SENTENCE. I don’t just want to see the answer! I want to see how students are solving the problem so I know that they understand why 11-5 = 6.

Please let me know if you have any questions!

Happy Learning!!!