This whole group Activboard lesson can be used to introduce the concept of area. I use this lesson to introduce the concept of area at the beginning of my unit. This Activiboard lesson aligns with the Common Core. My kids love coming up to the Activboard during this lesson to show what they know about area.
There are several more slides included in the product that will allow the kids to practice finding area. Also, there are a couple slides with word problems related to area.