diff --git a/src/handler/handler.go b/src/handler/handler.go
index 89141f6..faf8bda 100644
--- a/src/handler/handler.go
+++ b/src/handler/handler.go
@@ -20,10 +20,12 @@ func NewHandler(db *sqlx.DB) *Handler {
 	return &Handler{db: db}
 }
 
+// /ping
 func (h *Handler) PingHandler(c echo.Context) error {
 	return c.String(http.StatusOK, "pong")
 }
 
+// /lecture/byFolder/id/:folderId
 func (h *Handler) GetLectureByFolderIDHandler(c echo.Context) error {
 	folderID, err := strconv.Atoi(c.Param("folderId"))
 	if err != nil {
@@ -54,8 +56,9 @@ func (h *Handler) GetLectureByFolderIDHandler(c echo.Context) error {
 	return c.JSON(http.StatusOK, lecturesWithFolderPath)
 }
 
+// /lecture/byFolder/path
 func (h *Handler) GetLectureByFolderPathHandler(c echo.Context) error {
-	folderPath := c.Param("folderPath")
+	folderPath := c.QueryParam("folderPath")
 
 	folderPath = "/" + strings.ReplaceAll(folderPath, "-", " /")
 	lectures := []LectureFromDB{}
@@ -80,3 +83,46 @@ func (h *Handler) GetLectureByFolderPathHandler(c echo.Context) error {
 
 	return c.JSON(http.StatusOK, lecturesWithFolderPath)
 }
+
+// /lecture/folder/:folderId
+func (h *Handler) GetLectureChildFolderHandler(c echo.Context) error {
+	folderID, err := strconv.Atoi(c.Param("folderId"))
+	if err != nil {
+		log.Printf("failed to convert folderId to int: %v", err)
+		return c.JSON(http.StatusBadRequest, err)
+	}
+
+	files := []File{}
+	
+	childFolders := []FolderFromDB{}
+	err = h.db.Select(&childFolders, "SELECT * FROM folders WHERE parent_id = ?", folderID)
+	if err != nil && !errors.Is(err, sql.ErrNoRows) {
+		log.Printf("failed to get child folders: %v", err)
+		return c.JSON(http.StatusInternalServerError, err)
+	}
+
+	for _, folder := range childFolders {
+		files = append(files, File{
+			ID:       folder.ID,
+			Name:     folder.Name,
+			IsFolder: true,
+		})
+	}
+
+	childLectures := []LectureOnlyName{}
+	err = h.db.Select(&childLectures, "SELECT id, title FROM lectures WHERE folder_id = ?", folderID)
+	if err != nil && !errors.Is(err, sql.ErrNoRows) {
+		log.Printf("failed to get child lectures: %v", err)
+		return c.JSON(http.StatusInternalServerError, err)
+	}
+
+	for _, lecture := range childLectures {
+		files = append(files, File{
+			ID:       lecture.ID,
+			Name:     lecture.Title,
+			IsFolder: false,
+		})
+	}
+
+	return c.JSON(http.StatusOK, files)
+}
\ No newline at end of file
diff --git a/src/handler/model.go b/src/handler/model.go
index 193f69d..607bb2c 100644
--- a/src/handler/model.go
+++ b/src/handler/model.go
@@ -14,3 +14,19 @@ type Lecture struct {
 	Content    string `json:"content"`
 	FolderPath string `json:"folderpath"`
 }
+
+type FolderFromDB struct {
+	ID   int    `db:"id"`
+	Name string `db:"name"`
+}
+
+type File struct {
+	ID       int    `json:"id"`
+	Name     string `json:"name"`
+	IsFolder bool   `json:"isFolder"`
+}
+
+type LectureOnlyName struct {
+	ID    int    `db:"id"`
+	Title string `db:"title"`
+}