Kosakata merupakan komponen bahasa paling penting. Kosakata Bahasa Inggris akan mudah diterima oleh anak dengan kegiatan yang menarik dan menyenangkan. Penelitian ini bertujuan  melihat keefektifan buku ajar Happy Thinking untuk menambah kosakata pada anak usia dini. Metode penelitian ini ialah eksperimen. Penelitian ini mempunyai tujuan meneliti kemungkinan sebab akibat menggunakan satu atau lebih kondisi perlakuan pada peserta didik dengan model one group pre-test dan post-test, teknik pengumpulan data melalui observasi dan teknik analisis berupa analisis statistik. Dari hasil temuan penelitian bahwa siswa di Aisyiyah 41 Tegalharjo masih kurang dalam penguasaan kosakata bahasa inggris. Upaya dalam mengatasi hal tersebut dengan menstimulasi kemampuan bahasa asing anak usia dini yaitu memanfaatkan buku ajar happy thinking. Buku ajar happy thinking menjadi bahan ajar Bahasa Inggris agar siswa menyerap kosakata secara mudah, karena desain buku yang menarik dan kosakata sederhana yang mudah dipahami oleh anak

This study aims to improve the social and emotional development of early childhoodduring the pandemic. The Covid-19 pandemic has an effect on AUD playing activities.Children must stay at home so that they do not play socializing with their friends, so theapplication is carried out, namely collaboration between parents and teachers throughpositive habituation. This study used a descriptive qualitative research design with a casestudy approach. In this study, the writer wanted to explore learning problems through several journal sources, especially in the social emotional development carried out at home. From the results of the analysis, the researcher could get the results of the collaboration between parents and increase children's emotional social, namely parents or educators who have an important role in educating for children's growth and development. The implication of the application of daily habituation and teacher collaboration includes taking the processof child development through daily habituation and always paying attention to learning, making children enthusiastic, because parents have an important role in child development. Parents and teachers in conveying learning and taking good care by giving freedom to children can develop children's ideas or imaginations. The emotional development of children can be seen from their daily activities that are independent, responsible, and comfortable with their parents