diff --git a/src/app/learnocaml_index_main.ml b/src/app/learnocaml_index_main.ml
index d2011b9b9..883e65574 100644
--- a/src/app/learnocaml_index_main.ml
+++ b/src/app/learnocaml_index_main.ml
@@ -56,12 +56,20 @@ module El = struct
   module Dyn = struct
     (** Elements that are dynamically created (ids only) *)
     let exercise_list_id = "learnocaml-main-exercise-list"
+    let exercise_bar = "learnocaml-main-exercise-bar"
+    let exercise_pane = "learnocaml-main-exercise-pane"
+    let filter_box = "learnocaml-filter-box"
     let tutorial_id = "learnocaml-main-tutorial"
     let lesson_id = "learnocaml-main-lesson"
     let toplevel_id = "learnocaml-main-toplevel"
   end
 end
 
+type tab_handler =
+  (?clear_cache:bool -> unit -> unit Lwt.t) ->
+  (string -> string) * (string -> string -> unit) * (string -> unit) ->
+  unit -> Html_types.div H.elt t
+
 let show_loading msg = show_loading ~id:El.loading_id H.[ul [li [txt msg]]]
 
 let get_url token dynamic_url static_url id =
@@ -69,95 +77,244 @@ let get_url token dynamic_url static_url id =
   | Some _ -> dynamic_url ^ Url.urlencode id ^ "/"
   | None -> api_server ^ "/" ^ static_url ^ Url.urlencode id
 
-let exercises_tab token _ _ () =
-  show_loading [%i"Loading exercises"] @@ fun () ->
-  Lwt_js.sleep 0.5 >>= fun () ->
-  retrieve (Learnocaml_api.Exercise_index token)
-  >>= fun (index, deadlines) ->
-  let format_exercise_list all_exercise_states =
-    let rec format_contents lvl acc contents =
-      let open Tyxml_js.Html5 in
-      match contents with
-      | Exercise.Index.Exercises exercises ->
-          List.fold_left
-            (fun acc (exercise_id, meta_opt) ->
-              match meta_opt with None -> acc | Some meta ->
-              let {Exercise.Meta.kind; title; short_description; stars; _ } =
-                meta
+type exercise_ordering = By_category | By_skill | By_difficulty
+
+let (exercise_filter_signal: string option React.signal), set_exercise_filter =
+  React.S.create None
+
+let (exercise_sort_signal: exercise_ordering React.signal), set_exercise_sort =
+  React.S.create By_category
+
+let make_exercises_to_display_signal index =
+  let get_index exo_sort exo_filter =
+    let index =
+      match exo_sort with
+      | By_category -> index
+      | By_skill ->
+          let module StrMap = Map.Make(struct
+              type t = string
+              (* Case-insensitive ordering *)
+              let compare a b =
+                String.(compare (lowercase_ascii a) (lowercase_ascii b))
+            end)
+          in
+          let by_skill =
+            Exercise.Index.fold_exercises (fun map id meta ->
+                List.fold_left (fun acc skill ->
+                    StrMap.update skill
+                      (function None -> Some [id, Some meta]
+                              | Some l -> Some ((id, Some meta) :: l))
+                      acc)
+                  map
+                  meta.Exercise.Meta.focus)
+              StrMap.empty index
+          in
+          let groups =
+            StrMap.fold (fun skill exercises acc ->
+                (skill,
+                 {Exercise.Index.title = skill;
+                  contents = Exercise.Index.Exercises (List.rev exercises)})
+                :: acc)
+              by_skill []
+          in
+          Exercise.Index.Groups (List.rev groups)
+      | By_difficulty ->
+          let module IntMap = Map.Make(Int) in
+          let starmap =
+            Exercise.Index.fold_exercises (fun map id meta ->
+                IntMap.update
+                  (int_of_float (Float.ceil meta.Exercise.Meta.stars))
+                  (function None -> Some [id, Some meta]
+                          | Some l -> Some ((id, Some meta) :: l))
+                  map)
+              IntMap.empty index
+          in
+          let groups =
+            IntMap.fold (fun stars exercises acc ->
+                let title =
+                  if stars = 1 then [%i"1 star"]
+                  else Printf.sprintf [%if"%d stars"] stars
+                in
+                (title,
+                 {Exercise.Index.title;
+                  contents = Exercise.Index.Exercises (List.rev exercises)})
+                :: acc)
+              starmap []
+          in
+          Exercise.Index.Groups (List.rev groups)
+    in
+    let index =
+      match exo_filter with
+      | None -> index
+      | Some filt_str ->
+          Exercise.Index.filter (fun _ meta ->
+              let re = Re.(compile (no_case (str filt_str))) in
+              List.exists (Re.execp re)
+                (meta.Exercise.Meta.title ::
+                 Option.to_list meta.Exercise.Meta.short_description @
+                 List.map fst meta.Exercise.Meta.author @
+                 List.map snd meta.Exercise.Meta.author @
+                 meta.Exercise.Meta.focus @
+                 meta.Exercise.Meta.requirements))
+            index
+    in
+    if index = Exercise.Index.Exercises [] then
+      Exercise.Index.Groups
+        ["empty_group",
+         { Exercise.Index.title = [%i"No exercises found"];
+           Exercise.Index.contents = Exercise.Index.Exercises []; }]
+    else index
+  in
+  React.S.l2 get_index exercise_sort_signal exercise_filter_signal
+
+let retain_signals = ref (React.S.const ())
+(* Used to register signals as GC roots *)
+
+let exercises_tab token : tab_handler =
+  fun _ _ () ->
+    let open Tyxml_js.Html5 in
+    show_loading  [%i"Loading exercises"] @@ fun () ->
+    Lwt_js.sleep 0.5 >>= fun () ->
+    retrieve (Learnocaml_api.Exercise_index token)
+    >>= fun (index, deadlines) ->
+    let exercises_to_display_signal =
+      make_exercises_to_display_signal index
+    in
+    let all_exercise_states =
+      Learnocaml_local_storage.(retrieve all_exercise_states)
+    in
+    let format_exercise exercise_id {Exercise.Meta.kind; title; short_description; stars; _ } =
+      let pct_init =
+        match SMap.find exercise_id all_exercise_states with
+        | exception Not_found -> None
+        | { Answer.grade ; _ } -> grade in
+      let pct_signal, pct_signal_set = React.S.create pct_init in
+      Learnocaml_local_storage.(listener (exercise_state exercise_id)) :=
+        Some (function
+            | Some { Answer.grade ; _ } -> pct_signal_set grade
+            | None -> pct_signal_set None) ;
+      let pct_text_signal =
+        React.S.map
+          (function
+            | None -> "--"
+            | Some 0 -> "0%"
+            | Some pct -> string_of_int pct ^ "%")
+          pct_signal in
+      let time_left = match List.assoc_opt exercise_id deadlines with
+        | None -> ""
+        | Some 0. -> [%i"Exercise closed"]
+        | Some f -> Printf.sprintf [%if"Time left: %s"]
+                      (string_of_seconds (int_of_float f))
+      in
+      let status_classes_signal =
+        React.S.map
+          (function
+            | None -> [ "stats" ]
+            | Some 0 -> [ "stats" ; "failure" ]
+            | Some pct when  pct >= 100 -> [ "stats" ; "success" ]
+            | Some _ -> [ "stats" ; "partial" ])
+          pct_signal in
+      a ~a:[ a_href (get_url token "/exercises/" "exercise.html#id=" exercise_id) ;
+             a_class [ "exercise" ] ] [
+        div ~a:[ a_class [ "descr" ] ] (
+          h1 [ txt title ] ::
+          begin match short_description with
+            | None -> []
+            | Some text -> [ txt text ]
+          end
+        );
+        div ~a:[ a_class [ "time-left" ] ] [H.txt time_left];
+        div ~a:[ Tyxml_js.R.Html5.a_class status_classes_signal ] [
+          stars_div stars;
+          div ~a:[ a_class [ "length" ] ] [
+            match kind with
+            | Exercise.Meta.Project -> txt [%i"project"]
+            | Exercise.Meta.Problem -> txt [%i"problem"]
+            | Exercise.Meta.Exercise -> txt [%i"exercise"] ] ;
+          div ~a:[ a_class [ "score" ] ] [
+            Tyxml_js.R.Html5.txt pct_text_signal
+          ]
+        ] ]
+    in
+    let rec format_exercise_list index =
+      match index with
+      | Exercise.Index.Exercises el ->
+          H.ul @@
+          List.map
+            (fun (id, meta) -> H.li [format_exercise id (Option.get meta)])
+            el
+      | Exercise.Index.Groups gl ->
+          H.ul @@
+          List.map (fun (id, grp) ->
+              let clas =
+                "group-title" ::
+                match gl with [] | [_] -> [] | _ -> ["collapsed"]
               in
-              let pct_init =
-                match SMap.find exercise_id all_exercise_states with
-                | exception Not_found -> None
-                | { Answer.grade ; _ } -> grade in
-              let pct_signal, pct_signal_set = React.S.create pct_init in
-              Learnocaml_local_storage.(listener (exercise_state exercise_id)) :=
-                Some (function
-                    | Some { Answer.grade ; _ } -> pct_signal_set grade
-                    | None -> pct_signal_set None) ;
-              let pct_text_signal =
-                React.S.map
-                  (function
-                    | None -> "--"
-                    | Some 0 -> "0%"
-                    | Some pct -> string_of_int pct ^ "%")
-                  pct_signal in
-              let time_left = match List.assoc_opt exercise_id deadlines with
-                | None -> ""
-                | Some 0. -> [%i"Exercise closed"]
-                | Some f -> Printf.sprintf [%if"Time left: %s"]
-                              (string_of_seconds (int_of_float f))
+              let title =
+                H.div ~a:[a_id id; a_class clas]
+                  [H.txt grp.Exercise.Index.title];
               in
-              let status_classes_signal =
-                React.S.map
-                  (function
-                    | None -> [ "stats" ]
-                    | Some 0 -> [ "stats" ; "failure" ]
-                    | Some pct when  pct >= 100 -> [ "stats" ; "success" ]
-                    | Some _ -> [ "stats" ; "partial" ])
-                  pct_signal in
-              a ~a:[ a_href (get_url token "/exercises/" "exercise.html#id=" exercise_id) ;
-                     a_class [ "exercise" ] ] [
-                div ~a:[ a_class [ "descr" ] ] (
-                  h1 [ txt title ] ::
-                  begin match short_description with
-                    | None -> []
-                    | Some text -> [ txt text ]
-                  end
-                );
-                div ~a:[ a_class [ "time-left" ] ] [H.txt time_left];
-                div ~a:[ Tyxml_js.R.Html5.a_class status_classes_signal ] [
-                  stars_div stars;
-                  div ~a:[ a_class [ "length" ] ] [
-                    match kind with
-                    | Exercise.Meta.Project -> txt [%i"project"]
-                    | Exercise.Meta.Problem -> txt [%i"problem"]
-                    | Exercise.Meta.Exercise -> txt [%i"exercise"] ] ;
-                  div ~a:[ a_class [ "score" ] ] [
-                    Tyxml_js.R.Html5.txt pct_text_signal
-                  ]
-                ] ] ::
-              acc)
-            acc exercises
-      | Exercise.Index.Groups groups ->
-          let h = match lvl with 1 -> h1 | 2 -> h2 | _ -> h3 in
-          List.fold_left
-            (fun acc (_, Exercise.Index.{ title ; contents }) ->
-               format_contents (succ lvl)
-                 (h ~a:[ a_class [ "pack" ] ] [ txt title ] :: acc)
-                 contents)
-            acc groups in
-    List.rev (format_contents 1 [] index) in
-  let list_div =
-    match format_exercise_list
-            Learnocaml_local_storage.(retrieve all_exercise_states)
-    with
-    | [] -> H.div [H.txt [%i"No open exercises at the moment"]]
-    | l -> H.div ~a:[H.a_id El.Dyn.exercise_list_id] l
-  in
-    Manip.appendChild El.content list_div;
-    Lwt.return list_div
+              let exos = format_exercise_list grp.Exercise.Index.contents in
+              Manip.Ev.onclick title
+                (fun _ ->
+                   ignore (Manip.toggleClass title "collapsed");
+                   false);
+              H.li [title; exos])
+            gl
+    in
+    let exercise_list_signal =
+      React.S.l1 format_exercise_list exercises_to_display_signal
+    in
+    let btns_sigs =
+      List.map (fun (id, sort, name) ->
+          let btn = button ~a:[a_id id] [ txt name ] in
+          Manip.Ev.onclick btn
+            (fun _ -> set_exercise_sort sort; true);
+          let signal =
+            React.S.map (fun s ->
+                (if sort = s then Manip.addClass else Manip.removeClass)
+                  btn "active"
+              ) exercise_sort_signal
+          in
+          btn, signal)
+        [
+          "by_category", By_category, [%i"By category"];
+          "by_skill", By_skill, [%i"By skill"];
+          "by_difficulty", By_difficulty, [%i"By difficulty"];
+        ]
+    in
+    let btns, btns_sigs = List.split btns_sigs in
+    let btns =
+      btns @
+      [
+        let input_field =
+          H.input ~a:[H.a_input_type `Search] ()
+        in
+        Manip.Ev.oninput input_field (fun _ev ->
+            set_exercise_filter (Some (Manip.value input_field));
+            true);
+        H.div ~a:[H.a_class ["filter-box"]] [input_field];
+      ]
+    in
+    let exercise_list_html =
+      H.div ~a:[H.a_id El.Dyn.exercise_list_id] btns
+    in
+    let pane_div =
+      H.div ~a:[H.a_id El.Dyn.exercise_pane]
+        [H.div ~a:[H.a_id El.Dyn.exercise_bar] btns; exercise_list_html]
+    in
+    Manip.removeChildren El.content;
+    Manip.appendChild El.content pane_div;
+    let list_update_signal =
+      React.S.map (fun l -> Manip.replaceChildren exercise_list_html [l])
+        exercise_list_signal
+    in
+    retain_signals :=
+      React.S.merge (fun () () -> ()) () (list_update_signal :: btns_sigs);
+    Lwt.return pane_div
 
-let playground_tab token _ _ () =
+let playground_tab token : tab_handler =
+  fun _ _ () ->
   show_loading [%i"Loading playground"] @@ fun () ->
   Lwt_js.sleep 0.5 >>= fun () ->
   retrieve (Learnocaml_api.Playground_index ())
@@ -183,7 +340,8 @@ let playground_tab token _ _ () =
   Manip.appendChild El.content list_div;
   Lwt.return list_div
 
-let lessons_tab select (arg, set_arg, _delete_arg) () =
+let lessons_tab : tab_handler =
+  fun select (arg, set_arg, _delete_arg) () ->
   show_loading [%i"Loading lessons"] @@ fun () ->
   Lwt_js.sleep 0.5 >>= fun () ->
   retrieve (Learnocaml_api.Lesson_index ()) >>= fun index ->
@@ -301,7 +459,8 @@ let lessons_tab select (arg, set_arg, _delete_arg) () =
   end >>= fun () ->
   Lwt.return lesson_div
 
-let tutorial_tab select (arg, set_arg, _delete_arg) () =
+let tutorial_tab : tab_handler =
+  fun select (arg, set_arg, _delete_arg) () ->
   let open Tutorial in
   let navigation_div =
     Tyxml_js.Html5.(div ~a: [ a_class [ "navigation" ] ] []) in
@@ -489,7 +648,8 @@ let tutorial_tab select (arg, set_arg, _delete_arg) () =
   init_toplevel_pane toplevel_launch top toplevel_buttons_group toplevel_button ;
   Lwt.return tutorial_div
 
-let toplevel_tab select _ () =
+let toplevel_tab : tab_handler =
+  fun select _ () ->
   let container =
     Tyxml_js.Html5.(div ~a: [ a_class [ "toplevel-pane" ] ]) [] in
   let buttons_div =
@@ -509,7 +669,8 @@ let toplevel_tab select _ () =
   init_toplevel_pane (Lwt.return top) top toplevel_buttons_group button ;
   Lwt.return div
 
-let teacher_tab token a b () =
+let teacher_tab token : tab_handler =
+  fun a b () ->
   show_loading [%i"Loading student info"] @@ fun () ->
   Learnocaml_teacher_tab.teacher_tab token a b () >>= fun div ->
   Lwt.return div
@@ -680,7 +841,7 @@ let () =
   in
   let init_tabs token =
     let get_opt o = Js.Optdef.get o (fun () -> false) in
-    let tabs =
+    let tabs : (string * (string * tab_handler)) list =
       (if get_opt config##.enableTutorials
        then [ "tutorials", ([%i"Tutorials"], tutorial_tab) ] else []) @
       (if get_opt config##.enableLessons
@@ -707,7 +868,7 @@ let () =
          let btn = Tyxml_js.Html5.(button [ txt name]) in
          let div = ref None in
          let args = ref [] in
-         let rec select () =
+         let rec select ?(clear_cache=false) () =
            let th () =
              Lwt.pause () >>= fun () ->
              begin match !current_btn with
@@ -715,13 +876,15 @@ let () =
                | Some btn -> Manip.removeClass btn "active"
              end ;
              Manip.removeChildren El.content ;
-             List.iter (fun (n, _) -> delete_arg n) !(!current_args) ;
+             List.iter (fun (n, _) ->
+              if n <> "display" then delete_arg n)
+              !(!current_args);
              begin match !div with
-               | Some div ->
+                | Some div when not clear_cache ->
                    List.iter (fun (n, v) -> set_arg n v) !args ;
                    Manip.appendChild El.content div ;
                    Lwt.return_unit
-               | None ->
+                | _ ->
                    let arg name =
                      arg name in
                    let set_arg name value =
diff --git a/src/state/learnocaml_data.ml b/src/state/learnocaml_data.ml
index 09f6b1b7b..9b94d7fda 100644
--- a/src/state/learnocaml_data.ml
+++ b/src/state/learnocaml_data.ml
@@ -1018,7 +1018,7 @@ module Exercise = struct
         List.fold_left (fun exs skill ->
             List.fold_left (fun exs id ->
                 (ex_node exercises id, [Skill skill]) :: exs)
-              exs (SMap.find skill focus)
+              exs (try SMap.find skill focus with Not_found -> [])
           ) exs ex_meta.Meta.requirements
       in
       let exs = merge_children exs in
@@ -1077,6 +1077,27 @@ module Exercise = struct
       in
       compute [] graph
 
+    let fold f acc graph =
+      let visited_nodes = Hashtbl.create 17 in
+      let rec fold_nodes acc graph =
+        let rec fold_children acc node =
+          if Hashtbl.mem visited_nodes node.name
+          then acc
+          else let acc =
+            List.fold_left
+              fold_children acc
+              (List.map fst node.children)
+          in
+          Hashtbl.add visited_nodes node.name ();
+          f acc node
+        in
+        match graph with
+        | [] -> acc
+        | node :: nodes ->
+          fold_nodes (fold_children acc node) nodes
+      in
+      fold_nodes acc graph
+
     let dump_dot fmt nodes =
       let print_kind fmt = function
         | Skill s -> Format.fprintf fmt "(S %s)" s
diff --git a/src/state/learnocaml_data.mli b/src/state/learnocaml_data.mli
index df4224a27..b80bb7ec5 100644
--- a/src/state/learnocaml_data.mli
+++ b/src/state/learnocaml_data.mli
@@ -345,6 +345,9 @@ module Exercise: sig
         exercise. *)
     val compute_exercise_set : node -> string list
 
+    (** Fold function that handles every exercise's dependency before handling exercise itself *)
+    val fold : ('a -> node -> 'a) -> 'a -> node list -> 'a
+
     (** Dumps the graph as a `dot` representation, into the given formatter. *)
     val dump_dot : Format.formatter -> node list -> unit
 
diff --git a/static/css/learnocaml_main.css b/static/css/learnocaml_main.css
index 27539cbb3..a18ee7105 100644
--- a/static/css/learnocaml_main.css
+++ b/static/css/learnocaml_main.css
@@ -418,16 +418,58 @@ body {
 
 /* -- Exercises activity --------------------------------------------------- */
 
-#learnocaml-main-exercise-list > .exercise + .exercise {
+#learnocaml-main-exercise-bar {
+  display: flex;
+  justify-content: space-between;
+  width: 100%;
+}
+
+#learnocaml-main-exercise-bar button {
+  flex-grow: 1;
+  background: linear-gradient(to bottom, #9bd 0%, #5581ff 100%);
+  color: #fff;
+  text-shadow: 0 0 10px #000;
+}
+
+#learnocaml-main-exercise-bar button.active {
+  background: linear-gradient(to bottom, #f29100 0%, #ec670f 100%);
+}
+
+#learnocaml-main-exercise-list .collapsed + ul {
+  display: none;
+}
+
+.filter-box input {
+    padding-left: 22px;
+    padding-right: 22px;
+}
+.filter-box::before {
+  position: absolute;
+  margin: 3px;
+  content: "🔍";
+  width: 16px;
+}
+
+#learnocaml-main-exercise-list ul {
+  list-style-type: none;
+  margin: 0;
+  padding: 0;
+}
+
+#learnocaml-main-exercise-list ul ul .group-title {
+  padding-left: 2em;
+}
+
+#learnocaml-main-exercise-list .exercise + .exercise {
   border-top: 1px #333 solid;
 }
-#learnocaml-main-exercise-list > .exercise {
+#learnocaml-main-exercise-list .exercise {
   position: relative;
   background: linear-gradient(to top, #aaa 0px, #eee 10px, #ddd 100%);
   color: black;
   text-decoration: none;
 }
-#learnocaml-main-exercise-list > .exercise:hover::after {
+#learnocaml-main-exercise-list .exercise:hover::after {
   position: absolute;
   background: #acf;
   opacity: 0.3;
@@ -435,20 +477,20 @@ body {
   left:0; right:0; bottom:0; top:0;
   content:"";
 }
-#learnocaml-main-exercise-list > .exercise > .descr {
+#learnocaml-main-exercise-list .exercise > .descr {
   padding: 10px;
   flex: 1 1 auto;
 }
-#learnocaml-main-exercise-list > .exercise > .descr > h1 {
+#learnocaml-main-exercise-list .exercise > .descr > h1 {
   margin: 0 0 10px 0; padding: 0;
   font-size: 18px;
   font-weight: bold;
 }
-#learnocaml-main-exercise-list > .exercise > .descr > p {
+#learnocaml-main-exercise-list .exercise > .descr > p {
   margin: 10px 0 0 0; padding: 0;
   text-align: justify;
 }
-#learnocaml-main-exercise-list > .pack {
+#learnocaml-main-exercise-list .group-title {
   padding: 10px;
   margin: 0;
   background: #222;
@@ -456,7 +498,15 @@ body {
   font-weight: bold;
   font-size: 20px;
   line-height: 26px;
+  cursor: pointer;
 }
+#learnocaml-main-exercise-list .group-title.collapsed::before {
+  content: "▶ ";
+}
+#learnocaml-main-exercise-list .group-title:not(.collapsed)::before {
+  content: "▼ ";
+}
+
 @media (min-width: 1000px) {
   #learnocaml-main-exercise-list {
     position: relative;
@@ -470,13 +520,13 @@ body {
   }
 }
 @media (min-width: 550px) {
-  #learnocaml-main-exercise-list > .exercise {
+  #learnocaml-main-exercise-list .exercise {
     display: flex;
     flex-direction: row;
     position: relative;
     z-index: 999;
   }
-  #learnocaml-main-exercise-list > .exercise > .stats {
+  #learnocaml-main-exercise-list .exercise > .stats {
     flex: 0;
     display: flex;
     flex-direction: column;
@@ -488,65 +538,65 @@ body {
     linear-gradient(to bottom, #bbb 0px, #ccc 36px, rgba(0,0,0,0) 36px),
     linear-gradient(to top, #999 0px, #ccc 10px);
   }
-  #learnocaml-main-exercise-list > .exercise > .stats > .stars {
+  #learnocaml-main-exercise-list .exercise > .stats > .stars {
     min-height: 20px;
     flex: 0 1 auto;
   }
-  #learnocaml-main-exercise-list > .exercise > .stats > .length {
+  #learnocaml-main-exercise-list .exercise > .stats > .length {
     flex: 1 1 auto;
   }
-  #learnocaml-main-exercise-list > .exercise > .stats > .score {
+  #learnocaml-main-exercise-list .exercise > .stats > .score {
     font-size: 20px;
     color: #666;
     flex: 0 1 auto;
   }
-  #learnocaml-main-exercise-list > .exercise > .stats.success {
+  #learnocaml-main-exercise-list .exercise > .stats.success {
     background:
     linear-gradient(to bottom, #7b6 0px, #8c7 36px, rgba(0,0,0,0) 36px),
     linear-gradient(to top, #483 0px, #8c7 10px);
   }
-  #learnocaml-main-exercise-list > .exercise > .stats.success > .score {
+  #learnocaml-main-exercise-list .exercise > .stats.success > .score {
     color: #080;
   }
-  #learnocaml-main-exercise-list > .exercise > .stats.failure {
+  #learnocaml-main-exercise-list .exercise > .stats.failure {
     background:
     linear-gradient(to bottom, #f44 0px, #f55 36px, rgba(0,0,0,0) 36px),
     linear-gradient(to top, #844 0px, #f55 10px);
   }
-  #learnocaml-main-exercise-list > .exercise > .stats.failure > .score {
+  #learnocaml-main-exercise-list .exercise > .stats.failure > .score {
     color: #800;
   }
-  #learnocaml-main-exercise-list > .exercise > .stats.partial {
+  #learnocaml-main-exercise-list .exercise > .stats.partial {
     background:
     linear-gradient(to bottom, #fc4 0px, #fd5 36px, rgba(0,0,0,0) 36px),
     linear-gradient(to top, #874 0px, #fd5 10px);
   }
-  #learnocaml-main-exercise-list > .exercise > .stats.partial > .score {
+  #learnocaml-main-exercise-list .exercise > .stats.partial > .score {
     color: #C80;
   }
 }
 @media (max-width: 549px) {
-  #learnocaml-main-exercise-list > .exercise {
+  #learnocaml-main-exercise-list .exercise {
     display: block;
     position: relative;
     z-index: 999;
   }
-  #learnocaml-main-exercise-list > .exercise > .stats > *,
-  #learnocaml-main-exercise-list > .exercise > .descr > * {
+  #learnocaml-main-exercise-list .exercise > .stats > *,
+  #learnocaml-main-exercise-list .exercise > .descr > * {
     position: relative;
     z-index: 1000;
   }
-  #learnocaml-main-exercise-list > .exercise > .descr > p {
+  #learnocaml-main-exercise-list .exercise > .descr > p {
     margin: 0 0 30px 0;
   }
-  #learnocaml-main-exercise-list > .exercise > .stats > .stars {
+  #learnocaml-main-exercise-list .exercise > .stats > .stars {
     position: absolute;
     line-height: 20px;
     height: 30px;
     bottom: 0; left: 10px;
     vertical-align: bottom;
   }
-  #learnocaml-main-exercise-list > .exercise > .stats > .length {
+  #learnocaml-main-exercise-list .exercise > .stats > .length {
     position: absolute;
     display: inline-block;
     line-height: 20px;
@@ -554,7 +604,7 @@ body {
     bottom: 0; left: 90px;
     vertical-align: bottom;
   }
-  #learnocaml-main-exercise-list > .exercise > .stats > .score {
+  #learnocaml-main-exercise-list .exercise > .stats > .score {
     width: 70px;
     text-align: center;
     font-size: 20px;
@@ -562,30 +612,30 @@ body {
     bottom: 15px; right: 10px;
     color: #666;
   }
-  #learnocaml-main-exercise-list > .exercise > .stats::after {
+  #learnocaml-main-exercise-list .exercise > .stats::after {
     background: linear-gradient(to top, #999 0px, #ccc 10px, rgba(0,0,0,0) 100%);
     bottom: 0; right: 0; top: 0; left: 0;
     content:"";
     position: absolute;
     z-index: 999;
   }
-  #learnocaml-main-exercise-list > .exercise > .stats.success::after {
+  #learnocaml-main-exercise-list .exercise > .stats.success::after {
     background: linear-gradient(to top, #483 0px, #8c7 10px, #8c7 100%);
   }
-  #learnocaml-main-exercise-list > .exercise > .stats.success > .score {
+  #learnocaml-main-exercise-list .exercise > .stats.success > .score {
     color: #080;
   }
-  #learnocaml-main-exercise-list > .exercise > .stats.failure::after {
+  #learnocaml-main-exercise-list .exercise > .stats.failure::after {
     background: linear-gradient(to top, #844 0px, #f55 10px);
   }
-  #learnocaml-main-exercise-list > .exercise > .stats.failure > .score {
+  #learnocaml-main-exercise-list .exercise > .stats.failure > .score {
     color: #800;
   }
-  #learnocaml-main-exercise-list > .exercise > .stats.partial::after {
+  #learnocaml-main-exercise-list .exercise > .stats.partial::after {
     background: linear-gradient(to top, #874 0px, #fd5 10px);
     color: #C80;
   }
-  #learnocaml-main-exercise-list > .exercise > .stats.partial > .score {
+  #learnocaml-main-exercise-list .exercise > .stats.partial > .score {
     color: #C80;
   }
 }
diff --git a/translations/fr.po b/translations/fr.po
index 6ce93eb5e..201aad75a 100644
--- a/translations/fr.po
+++ b/translations/fr.po
@@ -6,7 +6,7 @@
 msgid ""
 msgstr ""
 "Project-Id-Version: learn-ocaml ~dev\n"
-"PO-Revision-Date: 2023-08-28 09:10+0200\n"
+"PO-Revision-Date: 2023-10-24 16:44+0200\n"
 "Last-Translator: Erik Martin-Dorel <erik.martin-dorel@irit.fr>\n"
 "Language-Team: OCSF\n"
 "Language: french\n"
@@ -86,22 +86,22 @@ msgid "ERROR"
 msgstr "ERREUR"
 
 #: File "src/app/learnocaml_common.ml", line 140, characters 58-66 160, 30-38
-#: 455, 12-20 953, 19-27 "src/app/learnocaml_index_main.ml", 583, 17-25
+#: 455, 12-20 953, 19-27 "src/app/learnocaml_index_main.ml", 737, 17-25
 msgid "Cancel"
 msgstr "Annuler"
 
 #: File "src/app/learnocaml_common.ml", line 447, characters 26-41 948, 32-47
-#: "src/app/learnocaml_index_main.ml", 578,
+#: "src/app/learnocaml_index_main.ml", 732,
 msgid "REQUEST ERROR"
 msgstr "ERREUR DE REQUÊTE"
 
 #: File "src/app/learnocaml_common.ml", line 448, characters 22-59 949, 30-67
-#: "src/app/learnocaml_index_main.ml", 579, 28-65
+#: "src/app/learnocaml_index_main.ml", 733, 28-65
 msgid "Could not retrieve data from server"
 msgstr "Échec lors du téléchargement des données du serveur"
 
 #: File "src/app/learnocaml_common.ml", line 451, characters 12-19 495, 13-20
-#: 952, 19-26 "src/app/learnocaml_index_main.ml", 582, 17-24
+#: 952, 19-26 "src/app/learnocaml_index_main.ml", 736, 17-24
 msgid "Retry"
 msgstr "Réessayer"
 
@@ -138,17 +138,17 @@ msgid "No description available for this exercise."
 msgstr "Aucune description pour cet exercice."
 
 #: File "src/app/learnocaml_common.ml", line 643, characters 32-41
-#: "src/app/learnocaml_index_main.ml", 132, 54-63
+#: "src/app/learnocaml_index_main.ml", 224, 46-55
 msgid "project"
 msgstr "projet"
 
 #: File "src/app/learnocaml_common.ml", line 644, characters 32-41
-#: "src/app/learnocaml_index_main.ml", 133, 54-63
+#: "src/app/learnocaml_index_main.ml", 225, 46-55
 msgid "problem"
 msgstr "problème"
 
 #: File "src/app/learnocaml_common.ml", line 645, characters 33-43
-#: "src/app/learnocaml_index_main.ml", 134, 55-65
+#: "src/app/learnocaml_index_main.ml", 226, 47-57
 msgid "exercise"
 msgstr "exercice"
 
@@ -173,7 +173,7 @@ msgid "Editor"
 msgstr "Éditeur"
 
 #: File "src/app/learnocaml_common.ml", line 824, characters 41-51
-#: "src/app/learnocaml_index_main.ml", 692, 30-40
+#: "src/app/learnocaml_index_main.ml", 846, 30-40
 msgid "Toplevel"
 msgstr "Toplevel"
 
@@ -204,7 +204,7 @@ msgid "Stats"
 msgstr "Statistiques"
 
 #: File "src/app/learnocaml_common.ml", line 836, characters 37-48
-#: "src/app/learnocaml_index_main.ml", 689, 29-40
+#: "src/app/learnocaml_index_main.ml", 843, 29-40
 #: "src/app/learnocaml_teacher_tab.ml", 375, 21-32
 #: "src/app/learnocaml_exercise_main.ml", 204, 23-34
 msgid "Exercises"
@@ -232,12 +232,12 @@ msgid "This will discard all your edits. Are you sure?"
 msgstr "Toutes vos modifications seront perdues. Êtes-vous sûr·e ?"
 
 #: File "src/app/learnocaml_common.ml", line 944, characters 28-45 1180,
-#: "src/app/learnocaml_index_main.ml", 574,
+#: "src/app/learnocaml_index_main.ml", 728,
 msgid "TOKEN NOT FOUND"
 msgstr "TOKEN NON TROUVÉ"
 
 #: File "src/app/learnocaml_common.ml", line 945, characters 17-60 1181,
-#: "src/app/learnocaml_index_main.ml", 575,
+#: "src/app/learnocaml_index_main.ml", 729,
 msgid "The entered token couldn't be recognised."
 msgstr "Le token entré n'a pas été reconnu."
 
@@ -290,7 +290,7 @@ msgid "Show"
 msgstr "Montrer"
 
 #: File "src/app/learnocaml_common.ml", line 1171, characters 18-36
-#: "src/app/learnocaml_index_main.ml", 629, 31-49
+#: "src/app/learnocaml_index_main.ml", 783, 31-49
 msgid "Enter your token"
 msgstr "Entrez votre token"
 
@@ -412,174 +412,194 @@ msgstr ""
 msgid "The toplevel has been reset.\n"
 msgstr "Le toplevel a été redémarré.\n"
 
-#: File "src/app/learnocaml_index_main.ml", line 73, characters 18-37
+#: File "src/app/learnocaml_index_main.ml", line 128, characters 39-47
+msgid "1 star"
+msgstr "1 étoile"
+
+#: File "src/app/learnocaml_index_main.ml", line 129, characters 42-52
+msgid "%d stars"
+msgstr "%d étoiles"
+
+#: File "src/app/learnocaml_index_main.ml", line 157, characters 37-57
+msgid "No exercises found"
+msgstr "Aucun exercice trouvé"
+
+#: File "src/app/learnocaml_index_main.ml", line 169, characters 21-40
 msgid "Loading exercises"
 msgstr "Chargement des exercices"
 
-#: File "src/app/learnocaml_index_main.ml", line 106, characters 32-49
+#: File "src/app/learnocaml_index_main.ml", line 198, characters 24-41
 msgid "Exercise closed"
 msgstr "Exercice fermé"
 
-#: File "src/app/learnocaml_index_main.ml", line 107, characters 47-62
+#: File "src/app/learnocaml_index_main.ml", line 199, characters 39-54
 msgid "Time left: %s"
 msgstr "Temps restant: %s"
 
-#: File "src/app/learnocaml_index_main.ml", line 154, characters 28-61
-msgid "No open exercises at the moment"
-msgstr "Aucun exercice n'est encore ouvert"
+#: File "src/app/learnocaml_index_main.ml", line 274, characters 41-54
+msgid "By category"
+msgstr "Par catégorie"
+
+#: File "src/app/learnocaml_index_main.ml", line 275, characters 35-45
+msgid "By skill"
+msgstr "Par compétence"
+
+#: File "src/app/learnocaml_index_main.ml", line 276, characters 45-60
+msgid "By difficulty"
+msgstr "Par difficulté"
 
-#: File "src/app/learnocaml_index_main.ml", line 161, characters 18-38
+#: File "src/app/learnocaml_index_main.ml", line 311, characters 18-38
 msgid "Loading playground"
 msgstr "Chargement du bac-à-sable"
 
-#: File "src/app/learnocaml_index_main.ml", line 187, characters 18-35
+#: File "src/app/learnocaml_index_main.ml", line 338, characters 18-35
 msgid "Loading lessons"
 msgstr "Chargement des cours"
 
-#: File "src/app/learnocaml_index_main.ml", line 220, characters 37-61
+#: File "src/app/learnocaml_index_main.ml", line 371, characters 37-61
 msgid "Running OCaml examples"
 msgstr "Lancement des exemples d'OCaml"
 
-#: File "src/app/learnocaml_index_main.ml", line 261, characters 39-45 450,
+#: File "src/app/learnocaml_index_main.ml", line 412, characters 39-45 602,
 msgid "Prev"
 msgstr "Prec."
 
-#: File "src/app/learnocaml_index_main.ml", line 277, characters 40-46 467,
+#: File "src/app/learnocaml_index_main.ml", line 428, characters 40-46 619,
 msgid "Next"
 msgstr "Suiv."
 
-#: File "src/app/learnocaml_index_main.ml", line 334, characters 18-37
+#: File "src/app/learnocaml_index_main.ml", line 486, characters 18-37
 msgid "Loading tutorials"
 msgstr "Chargement des tutoriels"
 
-#: File "src/app/learnocaml_index_main.ml", line 500, characters 18-35
+#: File "src/app/learnocaml_index_main.ml", line 653, characters 18-35
 msgid "Launching OCaml"
 msgstr "Démarrage d'OCaml"
 
-#: File "src/app/learnocaml_index_main.ml", line 513, characters 18-40
+#: File "src/app/learnocaml_index_main.ml", line 667, characters 18-40
 msgid "Loading student info"
 msgstr "Chargement des informations sur les étudiants"
 
-#: File "src/app/learnocaml_index_main.ml", line 533, characters 22-46
+#: File "src/app/learnocaml_index_main.ml", line 687, characters 22-46
 msgid "Your Learn-OCaml token"
 msgstr "Votre token Learn-OCaml"
 
-#: File "src/app/learnocaml_index_main.ml", lines 534-535, characters 18-70
+#: File "src/app/learnocaml_index_main.ml", lines 688-689, characters 18-70
 msgid "Your token is displayed below. It identifies you and allows to share your workspace between devices."
 msgstr "Votre token est affiché ci-dessous. Il vous identifie et permet de partager un même espace de travail entre plusieurs machines."
 
-#: File "src/app/learnocaml_index_main.ml", line 536, characters 18-41
+#: File "src/app/learnocaml_index_main.ml", line 690, characters 18-41
 msgid "Please write it down."
 msgstr "Notez-le !"
 
-#: File "src/app/learnocaml_index_main.ml", line 617, characters 7-21
+#: File "src/app/learnocaml_index_main.ml", line 771, characters 7-21
 msgid "Connected as"
 msgstr "Connecté en tant que"
 
-#: File "src/app/learnocaml_index_main.ml", line 619, characters 7-19
+#: File "src/app/learnocaml_index_main.ml", line 773, characters 7-19
 msgid "Activities"
 msgstr "Activités"
 
-#: File "src/app/learnocaml_index_main.ml", line 621, characters 9-33
+#: File "src/app/learnocaml_index_main.ml", line 775, characters 9-33
 msgid "Welcome to Learn OCaml"
 msgstr "Bienvenue sur Learn OCaml"
 
-#: File "src/app/learnocaml_index_main.ml", line 622, characters 31-49
+#: File "src/app/learnocaml_index_main.ml", line 776, characters 31-49
 msgid "First connection"
 msgstr "Première connexion"
 
-#: File "src/app/learnocaml_index_main.ml", line 623, characters 36-66
+#: File "src/app/learnocaml_index_main.ml", line 777, characters 36-66
 msgid "New user? Create a new token"
 msgstr "Vous êtes nouveau ? Obtenez un nouveau token"
 
-#: File "src/app/learnocaml_index_main.ml", line 624, characters 38-57
+#: File "src/app/learnocaml_index_main.ml", line 778, characters 38-57
 msgid "Choose a nickname"
 msgstr "Choisissez un identifiant"
 
-#: File "src/app/learnocaml_index_main.ml", line 625, characters 38-46
+#: File "src/app/learnocaml_index_main.ml", line 779, characters 38-46
 msgid "Secret"
 msgstr "Secret"
 
-#: File "src/app/learnocaml_index_main.ml", line 626, characters 24-42
+#: File "src/app/learnocaml_index_main.ml", line 780, characters 24-42
 msgid "Create new token"
 msgstr "Nouveau token"
 
-#: File "src/app/learnocaml_index_main.ml", line 627, characters 24-40
+#: File "src/app/learnocaml_index_main.ml", line 781, characters 24-40
 msgid "Returning user"
 msgstr "Utilisateur existant"
 
-#: File "src/app/learnocaml_index_main.ml", line 628, characters 29-64
+#: File "src/app/learnocaml_index_main.ml", line 782, characters 29-64
 msgid "Already have a token? Click here!"
 msgstr "Vous avez déjà un token ? Par ici !"
 
-#: File "src/app/learnocaml_index_main.ml", line 630, characters 31-40
+#: File "src/app/learnocaml_index_main.ml", line 784, characters 31-40
 msgid "Connect"
 msgstr "Se connecter"
 
-#: File "src/app/learnocaml_index_main.ml", line 638, characters 9-19 640,
+#: File "src/app/learnocaml_index_main.ml", line 792, characters 9-19 794,
 #: "src/app/learnocaml_teacher_tab.ml", 612, 22-32
 msgid "Nickname"
 msgstr "Pseudonyme"
 
-#: File "src/app/learnocaml_index_main.ml", line 647, characters 7-48
+#: File "src/app/learnocaml_index_main.ml", line 801, characters 7-48
 msgid "Send feedback to Learn-OCaml developers"
 msgstr "Envoyer un commentaire aux développeurs Learn-OCaml"
 
-#: File "src/app/learnocaml_index_main.ml", line 676, characters 38-59
+#: File "src/app/learnocaml_index_main.ml", line 830, characters 38-59
 msgid "Choose an activity."
 msgstr "Sélectionnez une activité."
 
-#: File "src/app/learnocaml_index_main.ml", line 685, characters 31-42
+#: File "src/app/learnocaml_index_main.ml", line 839, characters 31-42
 msgid "Tutorials"
 msgstr "Tutoriels"
 
-#: File "src/app/learnocaml_index_main.ml", line 687, characters 29-38
+#: File "src/app/learnocaml_index_main.ml", line 841, characters 29-38
 msgid "Lessons"
 msgstr "Cours"
 
-#: File "src/app/learnocaml_index_main.ml", line 694, characters 32-44
+#: File "src/app/learnocaml_index_main.ml", line 848, characters 32-44
 #: "src/app/learnocaml_playground_main.ml", 77, 23-35
 msgid "Playground"
 msgstr "Bac-à-sable"
 
-#: File "src/app/learnocaml_index_main.ml", line 697, characters 28-35
+#: File "src/app/learnocaml_index_main.ml", line 851, characters 28-35
 msgid "Teach"
 msgstr "Enseignement"
 
-#: File "src/app/learnocaml_index_main.ml", line 795, characters 15-69
+#: File "src/app/learnocaml_index_main.ml", line 951, characters 15-69
 msgid "Be sure to write down your token before logging out:"
 msgstr "Assurez-vous d'avoir noté votre token :"
 
-#: File "src/app/learnocaml_index_main.ml", lines 797-799, characters 15-26
+#: File "src/app/learnocaml_index_main.ml", lines 953-955, characters 15-26
 msgid "WARNING: the data could not be synchronised with the server. Logging out will lose your local changes, be sure you exported a backup."
 msgstr "ATTENTION: l'espace de travail n'a pas pu être synchronisé avec le serveur. En vous déconnectant, vous perdrez tous les changements locaux, à moins d'avoir exporté votre espace de travail au préalable."
 
-#: File "src/app/learnocaml_index_main.ml", line 801, characters 22-30 45-53
-#: 823, 9-17
+#: File "src/app/learnocaml_index_main.ml", line 957, characters 22-30 45-53
+#: 979, 9-17
 msgid "Logout"
 msgstr "Déconnexion"
 
-#: File "src/app/learnocaml_index_main.ml", line 814, characters 9-21
+#: File "src/app/learnocaml_index_main.ml", line 970, characters 9-21
 msgid "Show token"
 msgstr "Afficher le token"
 
-#: File "src/app/learnocaml_index_main.ml", line 817, characters 9-25
+#: File "src/app/learnocaml_index_main.ml", line 973, characters 9-25
 msgid "Sync workspace"
 msgstr "Synchroniser"
 
-#: File "src/app/learnocaml_index_main.ml", line 820, characters 9-25
+#: File "src/app/learnocaml_index_main.ml", line 976, characters 9-25
 msgid "Export to file"
 msgstr "Exporter vers un fichier"
 
-#: File "src/app/learnocaml_index_main.ml", line 821, characters 9-17
+#: File "src/app/learnocaml_index_main.ml", line 977, characters 9-17
 msgid "Import"
 msgstr "Importer"
 
-#: File "src/app/learnocaml_index_main.ml", line 822, characters 9-36
+#: File "src/app/learnocaml_index_main.ml", line 978, characters 9-36
 msgid "Download all source files"
 msgstr "Télécharger tous les fichiers sources"
 
-#: File "src/app/learnocaml_index_main.ml", line 828, characters 38-44
+#: File "src/app/learnocaml_index_main.ml", line 984, characters 38-44
 msgid "Menu"
 msgstr "Menu"
 
@@ -1184,6 +1204,18 @@ msgstr ""
 msgid "Unexpected error:\n"
 msgstr "Erreur inattendue:\n"
 
+#~ msgid "By prerequisites"
+#~ msgstr "Par prérequis"
+
+#~ msgid "No open exercises at the moment"
+#~ msgstr "Aucun exercice n'est encore ouvert"
+
+#~ msgid "By legacy"
+#~ msgstr "Par groupe"
+
+#~ msgid "By order"
+#~ msgstr "Par ordre"
+
 #~ msgid "Draft not available."
 #~ msgstr "Brouillon non disponible."