Pada penelitian ini peneliti berfokus untuk mendeskripsikan dan menganalisis kesulitan yang dialami siswa dalam mengerjakan soal mengenai materi statistika. Metode penelitian menggunakan metode kualitatif dengan pendekatan saintifik. Subjek pada penelitian ini yaitu siswa SMP kelas IX E SMP Mahardika Batujajar dengan total responden sebanyak 20 siswa. Pengumpulan data menggunakan hasil tes siswa berdasarkan instrumen soal pada pokok bahasan statistika. Data yang digunakan berupa 5 butir soal uraian dan diberikan kepada subjek penelitian ini sebanyak 20 siswa. Indikator pencapaian kompetensi; 1) Menentukan median; 2) Membandingkan jumlah dari rata-rata; 3) Membuktikan median dari rata-rata; 4) Menganalisis suatu data; 5) Membuat dan mengambil keputusan, kemudian membuat memprediksi. Berlandaskan hasil penelitian yang dilakukan, analisis kesulitan siswa dalam mengerjakan soal pada materi statistika bahwa kesalahan paling banyak yang dikerjakan siswa terletak pada soal nomor 1 yang mempunyai indikator menentukan median pada suatu data dengan persentase kesalahan sampai 90% yang masuk kriteria sangat tinggi, faktor penyebab dari banyaknya kesalahan dibuat siswa adalah tidak memahami konsep dari soal dan kurang teliti dalam mengerjakan soal yang diberikan.

Mathematical understanding is a very important aspect and the basis for students' mathematical abilities, but the fact is that mathematical understanding is still difficult for students to do. Based on the results of initial observations found problems in learning mathematics, such as students still having difficulty in (a) applying mathematical concepts, (b) students do not play an active role in the learning process, (c) teachers still use the lecture method. As a result, students do not understand the subject matter well. So from this the purpose of this study was to develop a quizziz-assisted sequence and series module to measure students' mathematical understanding abilities. The research subjects were class XII students. The research method uses R D level 1 is research and development where this research will develop and validate products without product deployment. The indicators of mathematical understanding used are: (1) identifying the concepts studied, (2) predicting a problem using the sequence concept, (3) developing the concepts studied, (4) proving understanding of a concept, (5) applying the formula to cases simple. The instruments used were tests and non-tests. The test instrument is in the form of questions and non-tests in the form of a student attitude scale questionnaire. From the results of data processing, it was obtained from ICT experts getting a score of 85.12% which was categorized as very valid, from material experts getting a score of 79.5% which was categorized as valid, the practical category got a score of 76% which was categorized as practical and the effective category averaged 68.5% which in the good category.