Adding Three Single Digit Numbers

Two-digit by One-digit Addition Two-digit Addition Composing and Decomposing Numbers Adding 1 Addition Within 100 Addition and Ten Frames Adding Tens Repeated Addition Adding 3 Addition Within 10 Addition and Counting on Number Lines Adding Within 1000 Addition Within 20 Part-part-whole Relationships Making 10 Addition and Patterns of One More Doubles Facts Adding Three Numbers Doubles Plus 1 Adding Zero Adding with Zero Addition and Missing Addends Adding by 10s