This two-minute PowerPoint slideshow will help your students improve their mental subtraction skills, subtracting within 20 (Common Core 2.OA.B.2). Use this as a warm-up at the beginning of a whole-class math lesson or right before recess. Place it on student-computers for extra practice or as a rotation during Math Centers. 24 different subtraction problems. Each problem appears for five seconds and students say the answer aloud before the next slide appears with the answer. Quick. No prep. Just click and it runs itself (fully-automated).

Take a look at the Preview to see some of the slides in this slideshow. And if you want more Addition and Subtraction PowerPoint slideshows, then here are the rest in this series:

Add 10 to Two-digit Numbers

Add and Subtract within 20

Add Multiples of 10 (within 100)

Add Multiples of 10 (within 1000)

Mentally Add 10 to a Given Number

Mentally Add 100 to a Given Number

Mentally Add Three Numbers (within 20)

Subtract 10 from Multiples of 10

Subtract 10 from Two-digit Numbers

Subtract Multiples of 10 (within 100)

Subtract Multiples of 10 (within 1000)

Subtracting Hundreds (within 1000)

Two Minute Addition

Two Minute Multiplication

Two Minute Subtraction