This study is a qualitative case study research, determining the purposes of teachers to use the eTwinning platform and to examine the effects of the platform on teachers. The study group consisted of 15 volunteer teachers who carried out eTwinning projects rewarded with quality labels. In the study, the data were obtained through a semi-structured interview form, and the content analysis method was used in the data analysis. According to the results obtained, it was concluded that teachers used the eTwinning platform in order to make projects, participate in online courses, contribute to their professional development and collaborate. The platform has a great contribution to teachers both personally and professionally. As a result, it is obvious that the eTwinning platform is very useful for teachers. The platform is so effective that it contributes to the professional and personal development of teachers, and even changes their perspective on the profession.

Number sense is one of the topics studied by mathematics educators and researchers in recent years, and its importance is emphasized. The number of studies on number sense in our country is increasing day by day. The content analysis of these studies is thought to be a guiding guiding for teachers, mathematics educators and researchers and a guide for future studies. Therefore, the purpose of this study is to determine the tendency of number sense studies published in the field of mathematics education published as an article between 2011-2020 in Turkey. With this purpose 50 articles that meeting the specified criteria have been examined. In the analysis of the data, the "Article Review Form" was used and analyzed with content analysis, presented in tables with frequencies and percentages and interpreted in the light of this information. According to the findings of the research, it has been determined that the most of studies for number sense quantitative studies that using descriptive survey method. It was concluded that the target group of the studies was mostly aimed at primary school 5-8 students and the topic was studied with more than 100 samples. It was determined that the most that scale as a data collection tool and quantitative data analysis methods were used as a data analysis type. When the studies were examined according to the tendency of the topic, it was concluded that the studies focused on understanding the number sense more deeply and to measure the number sense.

Bu araştırmanın amacı salgın döneminde derslerini eş zamanlı uzaktan eğitim uygulamaları ile yürüten matematik öğretmenlerinin eş zamanlı uzaktan eğitim ile ilgili görüşlerinin belirlenmesidir. Çalışma nitel desenli bir durum çalışması şeklinde yürütülmüştür. Çalışma grubunu, derslerini eş zamanlı uzaktan eğitim uygulamaları ile yürüten 12 gönüllü matematik öğretmeni oluşturmaktadır. Veriler yarı yapılandırılmış görüşme formu ile toplanmıştır. Verilerin analizinde içerik analizi yöntemi kullanılmıştır. Eş zamanlı uzaktan eğitimin öğretmen görüşlerine göre teknoloji kullanımı konusunda, fiziksel açıdan, sağlık açısından ve zaman açısından avantajlı olduğu belirlenirken derslerin öğretmenler için yorucu olması, teknolojik araç ve alt yapı sorunlarının olması, öğretmenlerin çalışma saatlerinin çok fazla esnetilmesi, iletişim ve etkileşim eksikliği, ilgisizlik, eksik öğrenme gibi dezavantajları olduğu sonucuna ulaşılmıştır. Son olarak matematik öğretmenlerinin matematik derslerinde yüz yüze eğitim modelini tercih ettiği, az bir kısmının yüz yüze eğitim ve uzaktan eğitimin beraber olduğu karma modeli tercih ettiği sonucuna ulaşılmıştır.