hoiku-genba-ni-ikasu-kenshu-kai-no-mochi-ho-%e4%bf%9d%e8%82%b2%e7%8f%be%e5%a0%b4%e3%81%ab%e6%b4%bb%e3%81%8b%e3%81%99%e7%a0%94%e4%bf%ae%e4%bc%9a%e3%81%ae%e3%82%82%e3%81%a1%e6%96%b9-how-to-hold-works