Berdasarkan pengamatan yang dilakukan di kelas VII SMP XYZ di Lampung, peneliti menemukan bahwa banyak siswa yang memiliki pemahaman konsep yang rendah pada pelajaran matematika. Hal ini dikarenakan pengajaran yang terfokus dengan penerapan metode ceramah. Oleh karena itu, peneliti memutuskan untuk menerapkan metode Think Pair Share (TPS) untuk mengatasi masalah tersebut. Diharapkan melalui penerapan metode ini, tujuan penelitian dapat tercapai, yaitu meningkatkan pemahaman konsep melalui penerapan metode TPS dan mengetahui langkah-langkah penerapan metode TPS untuk meningkatkan pemahaman konsep siswa. Metode penelitian yang digunakan adalah metode Penelitian Tindakan Kelas (PTK) model Kemmis dan Taggart yang berlangsung selama tiga siklus. Penelitian dilaksanakan di kelas VII SMP XYZ di Lampung tanggal 3 Agustus 2015 – 3 November 2015. Peneliti menggunakan instrumen berikut untuk mendapatkan informasi, yakni lembar tes, lembar kuesioner siswa, lembar observasi mentor, jurnal refleksi peneliti dan lembar feedback mentor. Berdasarkan penelitian yang dilakukan, dapat disimpulkan bahwa penerapan metode TPS dapat meningkatkan pemahaman konsep persamaan dan pertidaksamaan linear satu variabel bagi siswa. Hal ini dapat dilihat dari peningkatan keberhasilan indikator yang dicapai pada setiap siklus./Based on the observation conducted in Grade VII SMP XYZ in Lampung, researcher found that there were many students who had low conceptual understanding on mathematics. This was because the learning was focused in lecture method. Therefore, researcher decided to apply Think Pair Share (TPS) method to solve that problem. Through the implementation of this method, researcher expected the research objectives could be achieved, which was to increase conceptual understanding through the application of the TPS method and to know the steps for implementing TPS method to improve students' conceptual understanding. The methodology used was the Class Action Research (CAR) method, Kemmis and Taggart model, which lasted for three cycles. Research conducted in the Grade VII SMP XYZ in Lampung on August 3rd, 2015 – November 3rd, 2015. Researcher used the following instruments to obtain information, such as worksheet, student’s questionnaire sheet, mentor’s observation sheet, researcher’s reflection journal, and mentor’s feedback sheet. Based on research conducted, it could be concluded that the application of TPS method could increase the conceptual understanding of students on One Variable Linear Equation and Inequality. It could be seen from the increased in the success of indicator that achieved in each cycle.