diff --git a/SL/aufgaben/devenv.lock b/SL/aufgaben/devenv.lock
deleted file mode 100644
index ca8e6d8..0000000
--- a/SL/aufgaben/devenv.lock
+++ /dev/null
@@ -1,103 +0,0 @@
-{
-  "nodes": {
-    "devenv": {
-      "locked": {
-        "dir": "src/modules",
-        "lastModified": 1779303056,
-        "narHash": "sha256-+DJSNTtrdUb5yelcKp8fa5aITlg050701WCOJt0oMtI=",
-        "owner": "cachix",
-        "repo": "devenv",
-        "rev": "0d0be23517b92cbcedd95a0dbb6f735deae9b38c",
-        "type": "github"
-      },
-      "original": {
-        "dir": "src/modules",
-        "owner": "cachix",
-        "repo": "devenv",
-        "type": "github"
-      }
-    },
-    "flake-compat": {
-      "flake": false,
-      "locked": {
-        "lastModified": 1767039857,
-        "narHash": "sha256-vNpUSpF5Nuw8xvDLj2KCwwksIbjua2LZCqhV1LNRDns=",
-        "owner": "edolstra",
-        "repo": "flake-compat",
-        "rev": "5edf11c44bc78a0d334f6334cdaf7d60d732daab",
-        "type": "github"
-      },
-      "original": {
-        "owner": "edolstra",
-        "repo": "flake-compat",
-        "type": "github"
-      }
-    },
-    "nixpkgs": {
-      "inputs": {
-        "nixpkgs-src": "nixpkgs-src"
-      },
-      "locked": {
-        "lastModified": 1778507786,
-        "narHash": "sha256-HzSQCKMsMr8r55LwM1JuzIOB+8bzk0FEv6sItKvsfoY=",
-        "owner": "cachix",
-        "repo": "devenv-nixpkgs",
-        "rev": "8f24a228a782e24576b155d1e39f0d914b380691",
-        "type": "github"
-      },
-      "original": {
-        "owner": "cachix",
-        "ref": "rolling",
-        "repo": "devenv-nixpkgs",
-        "type": "github"
-      }
-    },
-    "nixpkgs-python": {
-      "inputs": {
-        "flake-compat": "flake-compat",
-        "nixpkgs": [
-          "nixpkgs"
-        ]
-      },
-      "locked": {
-        "lastModified": 1779117433,
-        "narHash": "sha256-iKhNJH1ABTrPvDF6Sd1U+GCVYSh8Xn88ee10ko7PvvE=",
-        "owner": "cachix",
-        "repo": "nixpkgs-python",
-        "rev": "a0f88fb785debcb0a201d0ce311a2e3d829e4a1b",
-        "type": "github"
-      },
-      "original": {
-        "owner": "cachix",
-        "repo": "nixpkgs-python",
-        "type": "github"
-      }
-    },
-    "nixpkgs-src": {
-      "flake": false,
-      "locked": {
-        "lastModified": 1778274207,
-        "narHash": "sha256-I4puXmX1iovcCHZlRmztO3vW0mAbbRvq4F8wgIMQ1MM=",
-        "owner": "NixOS",
-        "repo": "nixpkgs",
-        "rev": "b3da656039dc7a6240f27b2ef8cc6a3ef3bccae7",
-        "type": "github"
-      },
-      "original": {
-        "owner": "NixOS",
-        "ref": "nixpkgs-unstable",
-        "repo": "nixpkgs",
-        "type": "github"
-      }
-    },
-    "root": {
-      "inputs": {
-        "devenv": "devenv",
-        "nixpkgs": "nixpkgs",
-        "nixpkgs-python": "nixpkgs-python"
-      }
-    }
-  },
-  "root": "root",
-  "version": 7
-}
\ No newline at end of file
diff --git a/SL/aufgaben/devenv.nix b/SL/aufgaben/devenv.nix
deleted file mode 100644
index 2f95820..0000000
--- a/SL/aufgaben/devenv.nix
+++ /dev/null
@@ -1,27 +0,0 @@
-{ pkgs, lib, config, ... }:
-
-{
-  languages.python = {
-    enable = true;
-    version = "3.12";
-    venv.enable = true;
-    venv.requirements = ''
-      ipython
-      jupyter
-      jupyterlab
-      numpy
-      pandas
-      matplotlib
-      seaborn
-      scikit-learn
-      imbalanced-learn
-      statsmodels
-      ydata-profiling
-    '';
-  };
-
-  packages = [
-    pkgs.graphviz
-    pkgs.zsh
-  ];
-}
diff --git a/SL/aufgaben/devenv.yaml b/SL/aufgaben/devenv.yaml
deleted file mode 100644
index f6e91f8..0000000
--- a/SL/aufgaben/devenv.yaml
+++ /dev/null
@@ -1,6 +0,0 @@
-inputs:
-  nixpkgs-python:
-    url: github:cachix/nixpkgs-python
-    inputs:
-      nixpkgs:
-        follows: nixpkgs
diff --git a/SL/aufgaben/workshop2/notebooks/ws2_feature_engineering.ipynb b/SL/aufgaben/workshop2/notebooks/ws2_feature_engineering.ipynb
index a861df1..17ab6e2 100644
--- a/SL/aufgaben/workshop2/notebooks/ws2_feature_engineering.ipynb
+++ b/SL/aufgaben/workshop2/notebooks/ws2_feature_engineering.ipynb
@@ -1891,7 +1891,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 35,
+   "execution_count": 37,
    "id": "864d7618",
    "metadata": {
     "scrolled": true
@@ -1908,6 +1908,27 @@
       "YearBuilt > 2018               0\n",
       "Koordinaten ausserhalb Melbourne: 0\n"
      ]
+    },
+    {
+     "data": {
+      "text/plain": [
+       "BuildingArea\n",
+       "120.0    119\n",
+       "100.0     96\n",
+       "110.0     96\n",
+       "130.0     90\n",
+       "115.0     87\n",
+       "150.0     82\n",
+       "112.0     74\n",
+       "140.0     72\n",
+       "90.0      72\n",
+       "104.0     70\n",
+       "Name: count, dtype: int64"
+      ]
+     },
+     "execution_count": 37,
+     "metadata": {},
+     "output_type": "execute_result"
     }
    ],
    "source": [
@@ -1929,7 +1950,11 @@
     "df[['Lattitude', 'Longtitude']].describe()\n",
     "weird = df[(df['Lattitude'] > -37) | (df['Lattitude'] < -39) |\n",
     "           (df['Longtitude'] < 144) | (df['Longtitude'] > 146)]\n",
-    "print(f'Koordinaten ausserhalb Melbourne: {len(weird)}')"
+    "print(f'Koordinaten ausserhalb Melbourne: {len(weird)}')\n",
+    "\n",
+    "# spikes\n",
+    "df['Landsize'].value_counts().head(10)\n",
+    "df['BuildingArea'].value_counts().head(10)"
    ]
   },
   {