diff --git a/main/CMakeLists.txt b/main/CMakeLists.txt
index 3aac623..ae6cf28 100644
--- a/main/CMakeLists.txt
+++ b/main/CMakeLists.txt
@@ -9,6 +9,7 @@ set(COMPONENT_SRCS
         "scenes/scene_demo.c"
         "scenes/scene_bootanim.c"
         "scenes/scene_menu.c"
+        "scenes/scene_number.c"
         "scenes/scene_test_menu.c"
         "graphics/nokia.c"
         "graphics/utf8.c"
diff --git a/main/liquid/liquid.c b/main/liquid/liquid.c
index 3e3c70d..05352d7 100644
--- a/main/liquid/liquid.c
+++ b/main/liquid/liquid.c
@@ -56,8 +56,8 @@ static struct SceneEvent handleSceneEvent(struct Liquid *container, struct Scene
             SLIST_REMOVE_HEAD(&container->stack, next);
             tag = topmost->scene->tag;
 
-            if (topmost->scene->free) {
-                topmost->scene->free(topmost->scene);
+            if (topmost->scene->deinit) {
+                topmost->scene->deinit(topmost->scene);
             }
             free(topmost->scene);
             free(topmost);
diff --git a/main/liquid/scene_type.h b/main/liquid/scene_type.h
index ab03b3d..e254dfd 100644
--- a/main/liquid/scene_type.h
+++ b/main/liquid/scene_type.h
@@ -56,13 +56,13 @@ typedef struct SceneEvent (*Scene_init_t)(struct Scene *scene);
 typedef void (*Scene_paint_t)(struct Scene *scene);
 
 /**
- * Scene::free fp type.
+ * Scene::deinit fp type.
  * Release internally allocated resources.
  * This is called by the GUI engine when the scene is closed.
  *
  * @param scene - self
  */
-typedef void (*Scene_free_t)(struct Scene *scene);
+typedef void (*Scene_deinit_t)(struct Scene *scene);
 
 /**
  * Scene instance in the framework
@@ -112,7 +112,7 @@ struct Scene {
      * Release internally allocated resources, if any. Called on close.
      * Nullable field.
      */
-    Scene_free_t free;
+    Scene_deinit_t deinit;
 };
 
 #endif //LIQUID_SCENE_TYPE_H
diff --git a/main/scenes/scene_car.c b/main/scenes/scene_car.c
index f84eb17..ba1f303 100644
--- a/main/scenes/scene_car.c
+++ b/main/scenes/scene_car.c
@@ -1,8 +1,9 @@
-#include "scenes.h"
-#include "liquid.h"
 #include <malloc.h>
+#include <inttypes.h>
 #include "graphics/nokia.h"
 #include "graphics/drawing.h"
+#include "scenes.h"
+#include "liquid.h"
 
 struct CarScene {
     struct Scene base;
diff --git a/main/scenes/scene_menu.c b/main/scenes/scene_menu.c
index f947054..17a5eb8 100644
--- a/main/scenes/scene_menu.c
+++ b/main/scenes/scene_menu.c
@@ -55,11 +55,18 @@ static struct SceneEvent onInput(struct MenuScene *self, struct InputEvent event
     }
 }
 
+static void deinit(struct MenuScene *self)
+{
+    free(self->items);
+    self->items = NULL;
+}
+
 struct MenuScene *NewScene_Menu(struct MenuItem *items, size_t items_len) {
     struct MenuScene *scene = calloc(1, sizeof(struct MenuScene));
 
     scene->base.paint = (Scene_paint_t) paint;
     scene->base.onInput = (Scene_onInput_t) onInput;
+    scene->base.deinit = (Scene_deinit_t) deinit;
 
     scene->items = items;
     scene->items_len = items_len;
diff --git a/main/scenes/scene_menu.h b/main/scenes/scene_menu.h
index e0ae98a..c649c1d 100644
--- a/main/scenes/scene_menu.h
+++ b/main/scenes/scene_menu.h
@@ -7,6 +7,9 @@
 #ifndef REFLOWER_SCENE_MENU_H
 #define REFLOWER_SCENE_MENU_H
 
+#include <stdint.h>
+#include <stddef.h>
+
 #define MENUITEM_LABEL_LEN 30
 
 struct MenuItem {
@@ -30,6 +33,8 @@ struct MenuScene {
     int32_t selected;
     // selection handler
     MenuScene_onSelect_t onSelect;
+    // Extra field for the instance's private use.
+    void *private;
 };
 
 struct MenuScene *NewScene_Menu(struct MenuItem *items, size_t items_len);
diff --git a/main/scenes/scene_number.c b/main/scenes/scene_number.c
new file mode 100644
index 0000000..058d86a
--- /dev/null
+++ b/main/scenes/scene_number.c
@@ -0,0 +1,66 @@
+#include "scenes.h"
+#include "liquid.h"
+#include <malloc.h>
+#include <stdio.h>
+#include "graphics/nokia.h"
+#include "graphics/drawing.h"
+#include "scene_number.h"
+
+struct NumberScene {
+    struct Scene base;
+    struct NumberSceneOpts *opts;
+};
+
+static struct SceneEvent onInput(struct NumberScene *self, struct InputEvent event) {
+    struct NumberSceneOpts *opts = self->opts;
+    switch (event.kind) {
+        case InputEventKind_Wheel:
+            opts->value += event.wheel.delta;
+
+            if (opts->value < opts->min) {
+                opts->value = opts->min;
+            }
+            else if (opts->value > opts->max) {
+                opts->value = opts->max;
+            }
+
+            return SceneEvent_Repaint();
+
+        case InputEventKind_Button:
+            if (event.button.state) {
+                return SceneEvent_Close(opts->value, NULL);
+            }
+            // fall through
+        default:
+            return SceneEvent_None();
+    }
+}
+
+static void paint(struct NumberScene *self)
+{
+    struct NumberSceneOpts *opts = self->opts;
+
+    LCD_clearDisplay(0);
+    LCD_setStrEx(opts->label, 1, 1, BLACK, FONT_BOLD);
+
+    char buf[10];
+    snprintf(buf, 10, "%d%s", opts->value, opts->unit);
+    LCD_setStrEx(buf, 1, 9, BLACK, FONT_DOUBLE);
+}
+
+static void deinit(struct NumberScene *self)
+{
+    free(self->opts);
+    self->opts = NULL;
+}
+
+struct Scene *NewScene_Number(struct NumberSceneOpts *opts) {
+    struct NumberScene *scene = calloc(1, sizeof(struct NumberScene));
+    if (!scene) return NULL;
+
+    scene->opts = opts;
+    scene->base.onInput = (Scene_onInput_t) onInput;
+    scene->base.paint = (Scene_paint_t) paint;
+    scene->base.deinit = (Scene_deinit_t) deinit;
+    return (struct Scene *) scene;
+}
diff --git a/main/scenes/scene_number.h b/main/scenes/scene_number.h
new file mode 100644
index 0000000..a215cf8
--- /dev/null
+++ b/main/scenes/scene_number.h
@@ -0,0 +1,32 @@
+/**
+ * TODO file description
+ * 
+ * Created on 2020/01/05.
+ */
+
+#ifndef REFLOWER_SCENE_NUMBER_H
+#define REFLOWER_SCENE_NUMBER_H
+
+#include <stdint.h>
+
+struct NumberSceneOpts {
+    char label[15];
+    char unit[8];
+    int32_t value;
+    int32_t min;
+    int32_t max;
+};
+
+/**
+ * Create number picker.
+ *
+ * The result is passed back as status.
+ *
+ * "opts" must be on heap and will be internally mutated.
+ *
+ * @param opts
+ * @return
+ */
+struct Scene *NewScene_Number(struct NumberSceneOpts *opts);
+
+#endif //REFLOWER_SCENE_NUMBER_H
diff --git a/main/scenes/scene_root.c b/main/scenes/scene_root.c
index 5e541f7..839753e 100644
--- a/main/scenes/scene_root.c
+++ b/main/scenes/scene_root.c
@@ -21,7 +21,7 @@ static struct SceneEvent init(struct RootScene *self)
     return SceneEvent_OpenChild(NewScene_Boot(), 1);
 }
 
-struct SceneEvent onChildReturn(struct RootScene *self, uint32_t tag, int32_t status, void *data)
+static struct SceneEvent onChildReturn(struct RootScene *self, uint32_t tag, int32_t status, void *data)
 {
     if (tag == 1) {
         return SceneEvent_OpenChild(NewScene_MenuTest(), 0);
diff --git a/main/scenes/scene_test_menu.c b/main/scenes/scene_test_menu.c
index e2ade1d..8602f82 100644
--- a/main/scenes/scene_test_menu.c
+++ b/main/scenes/scene_test_menu.c
@@ -10,8 +10,14 @@
 #include "scenes.h"
 #include "scene_menu.h"
 
+struct Priv {
+    int32_t number;
+    Scene_deinit_t parent_deinit;
+};
 
 static struct SceneEvent onSelect(struct MenuScene *self) {
+    struct Priv *priv = self->private;
+
     if (self->selected == 0) {
         return SceneEvent_Close(0, NULL);
     }
@@ -22,24 +28,55 @@ static struct SceneEvent onSelect(struct MenuScene *self) {
     if (self->selected == 9) {
         return SceneEvent_OpenChild(NewScene_Demo(), 0);
     }
+    if (self->selected == 2) {
+        struct NumberSceneOpts *opts = calloc(1, sizeof(struct NumberSceneOpts));
+        strcpy(opts->unit, "°C");
+        strcpy(opts->label, "Setpoint");
+        opts->value = priv->number;
+        opts->min = 0;
+        opts->max = 350;
+        return SceneEvent_OpenChild(NewScene_Number(opts), 99);
+    }
     if (self->selected == 5) {
         self->items[5].tag++;
-        snprintf(self->items[5].label, MENUITEM_LABEL_LEN, "Count = %d", self->items[5].tag);
+        snprintf(self->items[5].label, MENUITEM_LABEL_LEN, "Clicked %dx", self->items[5].tag);
         return SceneEvent_Repaint();
     }
 
     return SceneEvent_None();
 }
 
+static void deinit(struct MenuScene *self)
+{
+    struct Priv *priv = self->private;
+    if (priv->parent_deinit) {
+        priv->parent_deinit((struct Scene *) self);
+    }
+    free(self->private);
+    self->private = NULL;
+}
+
+static struct SceneEvent onChildReturn(struct MenuScene *self, uint32_t tag, int32_t status, void *data)
+{
+    struct Priv *priv = self->private;
+    if (tag == 99) {
+        priv->number = status;
+        snprintf(self->items[2].label, MENUITEM_LABEL_LEN, "Set=%d°C", priv->number);
+    }
+
+    // this should be unreachable
+    return SceneEvent_None();
+}
+
 struct Scene *NewScene_MenuTest() {
     struct MenuItem *items = calloc(10, sizeof(struct MenuItem));
 
     strncpy(items[0].label, "🔙Back", MENUITEM_LABEL_LEN);
     strncpy(items[1].label, "▶#1", MENUITEM_LABEL_LEN);
-    strncpy(items[2].label, "▶#2", MENUITEM_LABEL_LEN);
+    strncpy(items[2].label, "Set=0°C", MENUITEM_LABEL_LEN);
     strncpy(items[3].label, "▶#3", MENUITEM_LABEL_LEN);
     strncpy(items[4].label, "▶#4", MENUITEM_LABEL_LEN);
-    strncpy(items[5].label, "Count = 0", MENUITEM_LABEL_LEN);
+    strncpy(items[5].label, "Clicked 0x", MENUITEM_LABEL_LEN);
     strncpy(items[6].label, "▶#6", MENUITEM_LABEL_LEN);
     strncpy(items[7].label, "▶#7", MENUITEM_LABEL_LEN);
     strncpy(items[8].label, "Car", MENUITEM_LABEL_LEN);
@@ -48,5 +85,14 @@ struct Scene *NewScene_MenuTest() {
     struct MenuScene * scene = NewScene_Menu(items, 10);
     scene->onSelect = onSelect;
 
+    // private data added by the subclass
+    struct Priv *priv = calloc(1, sizeof(struct Priv));
+    priv->number = 0;
+    priv->parent_deinit = scene->base.deinit;
+    scene->private = priv;
+
+    scene->base.deinit = (Scene_deinit_t) deinit;
+    scene->base.onChildReturn = (Scene_onChildReturn_t) onChildReturn;
+
     return (struct Scene *) scene;
 }
diff --git a/main/scenes/scenes.h b/main/scenes/scenes.h
index 8e01735..1bf2809 100644
--- a/main/scenes/scenes.h
+++ b/main/scenes/scenes.h
@@ -7,11 +7,15 @@
 #ifndef REFLOWER_SCENES_H
 #define REFLOWER_SCENES_H
 
+#include "scene_type.h"
+
 struct Scene *NewScene_Root(void);
 struct Scene *NewScene_Boot(void);
 struct Scene *NewScene_Demo(void);
 struct Scene *NewScene_Car(void);
-
 struct Scene *NewScene_MenuTest(void);
 
+#include "scene_menu.h"
+#include "scene_number.h"
+
 #endif //REFLOWER_SCENES_H