Check the state curriculum guide. In Georgia, for example, teaching subtraction is encouraged but not mandatory. Calculate roughly how many lesson plans you will need to teach subtraction. When possible, reinforce the concept in other areas, such as art, music, physical education and English.
Review the numbers with the students. Again, check the state curriculum guide to know the expectations. Have them count as high as they can to give you an indication of how many numbers they remember. Use flash cards and ask what the numbers are. Do a quick assessment of addition to make sure they understand the concept clearly before moving on to subtraction. Review in math is essential to make sure students don't forget or miss out on key concepts.
Start with numbers less than five for the first lesson plans. Keep it simple and stick to a level they can understand. Use the concept of "take away" to explain subtraction and use tangible resources. You have five balls -- or pencils or books -- and you take away two and ask the students how many are left. Follow up with a worksheet for practice.
Increase the subtraction exercises numbers to 10. At this point, have the students begin thinking theoretically rather than counting the objects. Stay at this level until they are both comfortable with the concept and quick with the answers. Introduce two-digit numbers once students can work with one-digit numbers. This concept may be too advanced for kindergarten students, but if you have a class that is particularly good at math, they may be able to work with numbers up to 20 at this age.
Incorporate subtraction games into your lesson plans. Divide the students into teams and have them do subtraction drills. They have to collaborate to get the right answer to the flash card questions.
Test the students at the end of the lesson plans on subtraction. This can be verbal, written or a combination of both. Use the results to identify students who are weak at subtraction and require remedial work.