diff --git a/autokoopman/autokoopman.py b/autokoopman/autokoopman.py
index 9a210cb..371d3cf 100644
--- a/autokoopman/autokoopman.py
+++ b/autokoopman/autokoopman.py
@@ -5,7 +5,7 @@
 
 import numpy as np
 
-import autokoopman.core.observables as kobs
+import autokoopman.observable as kobs
 from autokoopman.core.trajectory import (
     TrajectoriesData,
     UniformTimeTrajectoriesData,
@@ -24,7 +24,7 @@
 from autokoopman.tuner.gridsearch import GridSearchTuner
 from autokoopman.tuner.montecarlo import MonteCarloTuner
 from autokoopman.tuner.bayesianopt import BayesianOptTuner
-from autokoopman.core.observables import KoopmanObservable
+from autokoopman.observable.observables import KoopmanObservable
 from autokoopman.core.format import hide_prints
 
 __all__ = ["auto_koopman"]
diff --git a/autokoopman/observable/__init__.py b/autokoopman/observable/__init__.py
new file mode 100644
index 0000000..f39f9e6
--- /dev/null
+++ b/autokoopman/observable/__init__.py
@@ -0,0 +1,2 @@
+from .observables import *
+from .rff import *
\ No newline at end of file
diff --git a/autokoopman/core/observables.py b/autokoopman/observable/observables.py
similarity index 77%
rename from autokoopman/core/observables.py
rename to autokoopman/observable/observables.py
index ff179a8..cf9a89b 100644
--- a/autokoopman/core/observables.py
+++ b/autokoopman/observable/observables.py
@@ -4,8 +4,6 @@
 import numpy as np
 import sympy as sp  # type: ignore
 
-from scipy.stats import cauchy, laplace
-
 
 class KoopmanObservable(abc.ABC):
     """
@@ -163,51 +161,3 @@ def __init__(self, dimension, degree) -> None:
 
     def obs_fcn(self, X: np.ndarray) -> np.ndarray:
         return self.poly.transform(np.atleast_2d(X)).T
-
-
-class RFFObservable(KoopmanObservable):
-    def __init__(self, dimension, num_features, gamma, metric="rbf"):
-        super(RFFObservable, self).__init__()
-        self.gamma = gamma
-        self.dimension = dimension
-        self.metric = metric
-        self.D = num_features
-        # Generate D iid samples from p(w)
-        if self.metric == "rbf":
-            self.w = np.sqrt(2 * self.gamma) * np.random.normal(
-                size=(self.D, self.dimension)
-            )
-        elif self.metric == "laplace":
-            self.w = cauchy.rvs(scale=self.gamma, size=(self.D, self.dimension))
-        # Generate D iid samples from Uniform(0,2*pi)
-        self.u = 2 * np.pi * np.random.rand(self.D)
-
-    def obs_fcn(self, X: np.ndarray) -> np.ndarray:
-        # modification...
-        if len(X.shape) == 1:
-            x = np.atleast_2d(X.flatten()).T
-        else:
-            x = X.T
-        w = self.w.T
-        u = self.u[np.newaxis, :].T
-        s = np.sqrt(2 / self.D)
-        Z = s * np.cos(x.T @ w + u.T)
-        return Z.T
-
-    def obs_grad(self, X: np.ndarray) -> np.ndarray:
-        if len(X.shape) == 1:
-            x = np.atleast_2d(X.flatten()).T
-        else:
-            x = X.T
-        x = np.atleast_2d(X.flatten()).T
-        w = self.w.T
-        u = self.u[np.newaxis, :].T
-        s = np.sqrt(2 / self.D)
-        # TODO: make this sparse?
-        Z = -s * np.diag(np.sin(u + w.T @ x).flatten()) @ w.T
-        return Z
-
-    def compute_kernel(self, X: np.ndarray) -> np.ndarray:
-        Z = self.transform(X)
-        K = Z.dot(Z.T)
-        return K
diff --git a/autokoopman/observable/rff.py b/autokoopman/observable/rff.py
new file mode 100644
index 0000000..19f4613
--- /dev/null
+++ b/autokoopman/observable/rff.py
@@ -0,0 +1,52 @@
+import numpy as np
+from scipy.stats import cauchy, laplace
+
+from .observables import KoopmanObservable
+
+
+class RFFObservable(KoopmanObservable):
+    def __init__(self, dimension, num_features, gamma, metric="rbf"):
+        super(RFFObservable, self).__init__()
+        self.gamma = gamma
+        self.dimension = dimension
+        self.metric = metric
+        self.D = num_features
+        # Generate D iid samples from p(w)
+        if self.metric == "rbf":
+            self.w = np.sqrt(2 * self.gamma) * np.random.normal(
+                size=(self.D, self.dimension)
+            )
+        elif self.metric == "laplace":
+            self.w = cauchy.rvs(scale=self.gamma, size=(self.D, self.dimension))
+        # Generate D iid samples from Uniform(0,2*pi)
+        self.u = 2 * np.pi * np.random.rand(self.D)
+
+    def obs_fcn(self, X: np.ndarray) -> np.ndarray:
+        # modification...
+        if len(X.shape) == 1:
+            x = np.atleast_2d(X.flatten()).T
+        else:
+            x = X.T
+        w = self.w.T
+        u = self.u[np.newaxis, :].T
+        s = np.sqrt(2 / self.D)
+        Z = s * np.cos(x.T @ w + u.T)
+        return Z.T
+
+    def obs_grad(self, X: np.ndarray) -> np.ndarray:
+        if len(X.shape) == 1:
+            x = np.atleast_2d(X.flatten()).T
+        else:
+            x = X.T
+        x = np.atleast_2d(X.flatten()).T
+        w = self.w.T
+        u = self.u[np.newaxis, :].T
+        s = np.sqrt(2 / self.D)
+        # TODO: make this sparse?
+        Z = -s * np.diag(np.sin(u + w.T @ x).flatten()) @ w.T
+        return Z
+
+    def compute_kernel(self, X: np.ndarray) -> np.ndarray:
+        Z = self.transform(X)
+        K = Z.dot(Z.T)
+        return K
\ No newline at end of file
diff --git a/notebooks/linear-model.ipynb b/notebooks/linear-model.ipynb
index e3dfdfe..6d44c19 100644
--- a/notebooks/linear-model.ipynb
+++ b/notebooks/linear-model.ipynb
@@ -41,7 +41,7 @@
    "metadata": {},
    "outputs": [],
    "source": [
-    "from autokoopman.core.observables import RFFObservable, PolynomialObservable, IdentityObservable\n",
+    "from autokoopman.observable import RFFObservable, PolynomialObservable, IdentityObservable\n",
     "\n",
     "# augment (combine) observables function\n",
     "# in this case, combine multiple lengthscales together\n",
@@ -192,7 +192,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.9.7"
+   "version": "3.9.0"
   }
  },
  "nbformat": 4,
diff --git a/test/unit_test/test_koopman.py b/test/unit_test/test_koopman.py
index ad4a24c..8165fef 100644
--- a/test/unit_test/test_koopman.py
+++ b/test/unit_test/test_koopman.py
@@ -12,7 +12,8 @@ def test_discrete_koopman(normalize):
     """tests the discrete time Koopman estimator"""
     from autokoopman.benchmark.pendulum import PendulumWithInput
     from autokoopman.core.trajectory import TrajectoriesData
-    from autokoopman.core.observables import IdentityObservable, RFFObservable
+    from autokoopman.observable.observables import IdentityObservable
+    from autokoopman.observable.rff import RFFObservable
     from autokoopman.estimator.koopman import KoopmanDiscEstimator
     import random
 
@@ -62,7 +63,8 @@ def test_cont_koopman(normalize):
     """tests the continuous time Koopman estimator"""
     from autokoopman.benchmark.pendulum import PendulumWithInput
     from autokoopman.core.trajectory import TrajectoriesData
-    from autokoopman.core.observables import IdentityObservable, RFFObservable
+    from autokoopman.observable.observables import IdentityObservable
+    from autokoopman.observable.rff import RFFObservable
     from autokoopman.estimator.koopman import KoopmanContinuousEstimator
     import random