This is a great activity to help children practice one more / one less. It can be used in a math center or as a lesson. Children get lots of practice up to 3 digit numbers and crossing boundaries of 10 and 100. Here is an example of the format of this lesson:An example of a task card setThere is a set of colorful 24 pack task cards. They are perfect for laminating or backing on card to be re-used. They make a great group work activity, an activity for math centre, extension work or a math activi