A ten-frame is a great math tool. You can use it to work on skills such as 1-1 correspondence, number and quantity matching, addition, and subtraction. A ten-frame allows students to manipulate objects to solve a problem and/or see the solution for a problem.
With a second ten-frame you can help your students reach a better understanding of teen numbers. Choose a teen number and have your students identify its numerals. Next fill one ten-frame completely. Continue adding objects to the second ten-frame while counting to your chosen number. Finally, analyze what you have together, writing the problem next to the ten-frame.
A large magnetic ten-frame from a school supply store such as Lakeshore provides a means to practice math skills with a large group. You can “think aloud” as you compose and decompose teen numbers. By presenting one teen number each day with the ten-frames, your students will quickly grasp the concept of a teen number being “ten ones and some further ones.” Vary your approach from day to day - at times present the number first, some of the time have the counters in place, and at other times start with the addition problem. In all cases talk about what you are doing and/or have your students explain the process.