Pembelajaran abad 21 adalah pembelajaran yang menciptakan kecakapan berpikir kritis dan penyelesaian masalah serta kemahiran memburu informasi dan berkomunikasi. Namun realitasnya kemampuan kecerdasan kritis siswa masih belum sepadan dengan hasil belajarnya. Kurangnya kemampuan berpandang kritis siswa menjadi masalah pendidikan secara lokal maupun nasional. Siswa Indonesia masih kurang memiliki kemampuan berpikir tingkat tinggi salah satunya berpikir kritis, terbukti dari data TIMSS (Trends in Mathematics and Social Research, 2015) menunjukkan ukuran kemahiran berpikir reflektif masih rendah di Indonesia. Berdasarkan uraian diatas, maka perlu dilakukan penelitian pengembangan tentang kelayakan dan keefektifan media card question berbasis masalah sebagai media pembelajaran kelas VI materi tata surya dan karakteristik anggota tata surya dengan tujuan siswa menjadi aktif dalam pembelajaran serta meningkatkan kemampuan berpikir kritis siswa. Penelitian ini menggunakan model pengembangan ADDIE, pengujian produk dilakukan pada siswa kelas VI SDN Bunul Rejo 2 Malang. Uji validitas ahli materi dan media masing-masing mendapat presentase 84% dan 86% dalam kategori sangat valid atau layak. Pada uji keefektifan didapati peningkatan ketrampilan berpikir kritis siswa dapat dilihat melalui uji N-gain dengan perolehan rata-rata 0,78 yang masuk dalam kategori tinggi. Hasil uji kepraktisan kepraktisan media question card dalam meningkatkan ketrampilan berpikir kritis siswa pada materi tata surya dan karakteristik anggota tata surya berdasarkan survei timbal balik siswa yang diperoleh dengan rata-rata 92% dalam kategori sangat valid atau praktis. 

21st century learning is learning that creates critical thinking and problem solving skills as well as information and communication skills. But in reality, students' critical thinking skills are still not commensurate with their learning outcomes. The low level of students' critical thinking is a problem for local and national education. Indonesian students still lack high-order thinking skills, one of which is critical thinking, as evidenced by TIMSS data (Trends in Mathematics and Social Research, 2015) showing that the measure of reflective thinking ability is still low in Indonesia. Based on the description above, it is necessary to conduct development research on the feasibility and effectiveness of problem-based card question media as a learning medium for class VI material on the solar system and the characteristics of members of the solar system with the aim of students being active in learning and improving their critical thinking skills. This study uses the ADDIE development model. Product testing was carried out on sixth grade students at SDN Bunul Rejo 2 Malang. The validity test of material and media experts respectively got a percentage of 84% and 86% in the very valid or proper category. In the effectiveness test, it was found that the increase in students' critical thinking skills can be seen through the N-gain test with an average acquisition of 0.78, which is in the high category. The results of the practicality test of the question card media in improving students' critical thinking skills on the material of the solar system and the characteristics of the members of the solar system based on student response questionnaires obtained an average of 92% in the very valid or practical category.