diff --git a/src/main/java/ca/joeltherrien/randomforest/CovariateRow.java b/src/main/java/ca/joeltherrien/randomforest/CovariateRow.java
index 181d80b..5802da1 100644
--- a/src/main/java/ca/joeltherrien/randomforest/CovariateRow.java
+++ b/src/main/java/ca/joeltherrien/randomforest/CovariateRow.java
@@ -1,5 +1,6 @@
 package ca.joeltherrien.randomforest;
 
+import ca.joeltherrien.randomforest.covariates.Covariate;
 import lombok.Getter;
 import lombok.RequiredArgsConstructor;
 
diff --git a/src/main/java/ca/joeltherrien/randomforest/Row.java b/src/main/java/ca/joeltherrien/randomforest/Row.java
index b762f15..ef263bf 100644
--- a/src/main/java/ca/joeltherrien/randomforest/Row.java
+++ b/src/main/java/ca/joeltherrien/randomforest/Row.java
@@ -1,6 +1,8 @@
 package ca.joeltherrien.randomforest;
 
 
+import ca.joeltherrien.randomforest.covariates.Covariate;
+
 import java.util.Map;
 
 public class Row<Y> extends CovariateRow {
diff --git a/src/main/java/ca/joeltherrien/randomforest/BooleanCovariate.java b/src/main/java/ca/joeltherrien/randomforest/covariates/BooleanCovariate.java
similarity index 97%
rename from src/main/java/ca/joeltherrien/randomforest/BooleanCovariate.java
rename to src/main/java/ca/joeltherrien/randomforest/covariates/BooleanCovariate.java
index 6e0743f..b57df47 100644
--- a/src/main/java/ca/joeltherrien/randomforest/BooleanCovariate.java
+++ b/src/main/java/ca/joeltherrien/randomforest/covariates/BooleanCovariate.java
@@ -1,4 +1,4 @@
-package ca.joeltherrien.randomforest;
+package ca.joeltherrien.randomforest.covariates;
 
 import lombok.Getter;
 import lombok.RequiredArgsConstructor;
diff --git a/src/main/java/ca/joeltherrien/randomforest/Covariate.java b/src/main/java/ca/joeltherrien/randomforest/covariates/Covariate.java
similarity index 93%
rename from src/main/java/ca/joeltherrien/randomforest/Covariate.java
rename to src/main/java/ca/joeltherrien/randomforest/covariates/Covariate.java
index 0cf40c8..75bc672 100644
--- a/src/main/java/ca/joeltherrien/randomforest/Covariate.java
+++ b/src/main/java/ca/joeltherrien/randomforest/covariates/Covariate.java
@@ -1,4 +1,8 @@
-package ca.joeltherrien.randomforest;
+package ca.joeltherrien.randomforest.covariates;
+
+import ca.joeltherrien.randomforest.CovariateRow;
+import ca.joeltherrien.randomforest.Row;
+import ca.joeltherrien.randomforest.tree.Split;
 
 import java.io.Serializable;
 import java.util.*;
diff --git a/src/main/java/ca/joeltherrien/randomforest/FactorCovariate.java b/src/main/java/ca/joeltherrien/randomforest/covariates/FactorCovariate.java
similarity index 98%
rename from src/main/java/ca/joeltherrien/randomforest/FactorCovariate.java
rename to src/main/java/ca/joeltherrien/randomforest/covariates/FactorCovariate.java
index ed4c4e9..cf48933 100644
--- a/src/main/java/ca/joeltherrien/randomforest/FactorCovariate.java
+++ b/src/main/java/ca/joeltherrien/randomforest/covariates/FactorCovariate.java
@@ -1,4 +1,4 @@
-package ca.joeltherrien.randomforest;
+package ca.joeltherrien.randomforest.covariates;
 
 import lombok.EqualsAndHashCode;
 
diff --git a/src/main/java/ca/joeltherrien/randomforest/NumericCovariate.java b/src/main/java/ca/joeltherrien/randomforest/covariates/NumericCovariate.java
similarity index 98%
rename from src/main/java/ca/joeltherrien/randomforest/NumericCovariate.java
rename to src/main/java/ca/joeltherrien/randomforest/covariates/NumericCovariate.java
index 014bbfc..155beee 100644
--- a/src/main/java/ca/joeltherrien/randomforest/NumericCovariate.java
+++ b/src/main/java/ca/joeltherrien/randomforest/covariates/NumericCovariate.java
@@ -1,4 +1,4 @@
-package ca.joeltherrien.randomforest;
+package ca.joeltherrien.randomforest.covariates;
 
 import lombok.Getter;
 import lombok.RequiredArgsConstructor;
diff --git a/src/main/java/ca/joeltherrien/randomforest/regression/MeanResponseCombiner.java b/src/main/java/ca/joeltherrien/randomforest/regression/MeanResponseCombiner.java
index 4923a32..57a3b35 100644
--- a/src/main/java/ca/joeltherrien/randomforest/regression/MeanResponseCombiner.java
+++ b/src/main/java/ca/joeltherrien/randomforest/regression/MeanResponseCombiner.java
@@ -1,6 +1,6 @@
 package ca.joeltherrien.randomforest.regression;
 
-import ca.joeltherrien.randomforest.ResponseCombiner;
+import ca.joeltherrien.randomforest.tree.ResponseCombiner;
 
 import java.util.List;
 import java.util.Set;
diff --git a/src/main/java/ca/joeltherrien/randomforest/tree/Forest.java b/src/main/java/ca/joeltherrien/randomforest/tree/Forest.java
index 30e222b..427d7ab 100644
--- a/src/main/java/ca/joeltherrien/randomforest/tree/Forest.java
+++ b/src/main/java/ca/joeltherrien/randomforest/tree/Forest.java
@@ -1,11 +1,9 @@
 package ca.joeltherrien.randomforest.tree;
 
 import ca.joeltherrien.randomforest.CovariateRow;
-import ca.joeltherrien.randomforest.ResponseCombiner;
 import lombok.Builder;
 
 import java.util.Collection;
-import java.util.List;
 
 @Builder
 public class Forest<Y> {
diff --git a/src/main/java/ca/joeltherrien/randomforest/tree/ForestTrainer.java b/src/main/java/ca/joeltherrien/randomforest/tree/ForestTrainer.java
index bae9f9f..76d4a70 100644
--- a/src/main/java/ca/joeltherrien/randomforest/tree/ForestTrainer.java
+++ b/src/main/java/ca/joeltherrien/randomforest/tree/ForestTrainer.java
@@ -1,8 +1,7 @@
 package ca.joeltherrien.randomforest.tree;
 
 import ca.joeltherrien.randomforest.Bootstrapper;
-import ca.joeltherrien.randomforest.Covariate;
-import ca.joeltherrien.randomforest.ResponseCombiner;
+import ca.joeltherrien.randomforest.covariates.Covariate;
 import ca.joeltherrien.randomforest.Row;
 import lombok.Builder;
 
diff --git a/src/main/java/ca/joeltherrien/randomforest/ResponseCombiner.java b/src/main/java/ca/joeltherrien/randomforest/tree/ResponseCombiner.java
similarity index 79%
rename from src/main/java/ca/joeltherrien/randomforest/ResponseCombiner.java
rename to src/main/java/ca/joeltherrien/randomforest/tree/ResponseCombiner.java
index e418fdd..bbcdd30 100644
--- a/src/main/java/ca/joeltherrien/randomforest/ResponseCombiner.java
+++ b/src/main/java/ca/joeltherrien/randomforest/tree/ResponseCombiner.java
@@ -1,4 +1,4 @@
-package ca.joeltherrien.randomforest;
+package ca.joeltherrien.randomforest.tree;
 
 import java.util.List;
 import java.util.stream.Collector;
diff --git a/src/main/java/ca/joeltherrien/randomforest/Split.java b/src/main/java/ca/joeltherrien/randomforest/tree/Split.java
similarity index 75%
rename from src/main/java/ca/joeltherrien/randomforest/Split.java
rename to src/main/java/ca/joeltherrien/randomforest/tree/Split.java
index 9804804..eb90273 100644
--- a/src/main/java/ca/joeltherrien/randomforest/Split.java
+++ b/src/main/java/ca/joeltherrien/randomforest/tree/Split.java
@@ -1,5 +1,6 @@
-package ca.joeltherrien.randomforest;
+package ca.joeltherrien.randomforest.tree;
 
+import ca.joeltherrien.randomforest.Row;
 import lombok.Data;
 
 import java.util.List;
diff --git a/src/main/java/ca/joeltherrien/randomforest/tree/SplitNode.java b/src/main/java/ca/joeltherrien/randomforest/tree/SplitNode.java
index 3f5dfdb..c00249a 100644
--- a/src/main/java/ca/joeltherrien/randomforest/tree/SplitNode.java
+++ b/src/main/java/ca/joeltherrien/randomforest/tree/SplitNode.java
@@ -1,6 +1,6 @@
 package ca.joeltherrien.randomforest.tree;
 
-import ca.joeltherrien.randomforest.Covariate;
+import ca.joeltherrien.randomforest.covariates.Covariate;
 import ca.joeltherrien.randomforest.CovariateRow;
 import lombok.Builder;
 
diff --git a/src/main/java/ca/joeltherrien/randomforest/tree/TreeTrainer.java b/src/main/java/ca/joeltherrien/randomforest/tree/TreeTrainer.java
index 94a1dad..fd83382 100644
--- a/src/main/java/ca/joeltherrien/randomforest/tree/TreeTrainer.java
+++ b/src/main/java/ca/joeltherrien/randomforest/tree/TreeTrainer.java
@@ -1,6 +1,7 @@
 package ca.joeltherrien.randomforest.tree;
 
 import ca.joeltherrien.randomforest.*;
+import ca.joeltherrien.randomforest.covariates.Covariate;
 import lombok.Builder;
 
 import java.util.*;
diff --git a/src/test/java/ca/joeltherrien/randomforest/covariates/FactorCovariateTest.java b/src/test/java/ca/joeltherrien/randomforest/covariates/FactorCovariateTest.java
index 1a22ce9..4f00c6d 100644
--- a/src/test/java/ca/joeltherrien/randomforest/covariates/FactorCovariateTest.java
+++ b/src/test/java/ca/joeltherrien/randomforest/covariates/FactorCovariateTest.java
@@ -1,7 +1,6 @@
 package ca.joeltherrien.randomforest.covariates;
 
 
-import ca.joeltherrien.randomforest.FactorCovariate;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.function.Executable;
 
diff --git a/src/test/java/ca/joeltherrien/randomforest/workshop/TrainForest.java b/src/test/java/ca/joeltherrien/randomforest/workshop/TrainForest.java
index 003256c..00ba886 100644
--- a/src/test/java/ca/joeltherrien/randomforest/workshop/TrainForest.java
+++ b/src/test/java/ca/joeltherrien/randomforest/workshop/TrainForest.java
@@ -1,15 +1,14 @@
 package ca.joeltherrien.randomforest.workshop;
 
 import ca.joeltherrien.randomforest.*;
+import ca.joeltherrien.randomforest.covariates.Covariate;
+import ca.joeltherrien.randomforest.covariates.NumericCovariate;
 import ca.joeltherrien.randomforest.regression.MeanResponseCombiner;
 import ca.joeltherrien.randomforest.regression.WeightedVarianceGroupDifferentiator;
-import ca.joeltherrien.randomforest.tree.Forest;
 import ca.joeltherrien.randomforest.tree.ForestTrainer;
 import ca.joeltherrien.randomforest.tree.TreeTrainer;
 
 import java.util.*;
-import java.util.stream.Collectors;
-import java.util.stream.IntStream;
 
 public class TrainForest {
 
diff --git a/src/test/java/ca/joeltherrien/randomforest/workshop/TrainSingleTree.java b/src/test/java/ca/joeltherrien/randomforest/workshop/TrainSingleTree.java
index 72654a8..6e5dd55 100644
--- a/src/test/java/ca/joeltherrien/randomforest/workshop/TrainSingleTree.java
+++ b/src/test/java/ca/joeltherrien/randomforest/workshop/TrainSingleTree.java
@@ -1,9 +1,9 @@
 package ca.joeltherrien.randomforest.workshop;
 
 
-import ca.joeltherrien.randomforest.Covariate;
+import ca.joeltherrien.randomforest.covariates.Covariate;
 import ca.joeltherrien.randomforest.CovariateRow;
-import ca.joeltherrien.randomforest.NumericCovariate;
+import ca.joeltherrien.randomforest.covariates.NumericCovariate;
 import ca.joeltherrien.randomforest.Row;
 import ca.joeltherrien.randomforest.regression.MeanResponseCombiner;
 import ca.joeltherrien.randomforest.regression.WeightedVarianceGroupDifferentiator;
diff --git a/src/test/java/ca/joeltherrien/randomforest/workshop/TrainSingleTreeFactor.java b/src/test/java/ca/joeltherrien/randomforest/workshop/TrainSingleTreeFactor.java
index e63f8cd..665675c 100644
--- a/src/test/java/ca/joeltherrien/randomforest/workshop/TrainSingleTreeFactor.java
+++ b/src/test/java/ca/joeltherrien/randomforest/workshop/TrainSingleTreeFactor.java
@@ -2,6 +2,9 @@ package ca.joeltherrien.randomforest.workshop;
 
 
 import ca.joeltherrien.randomforest.*;
+import ca.joeltherrien.randomforest.covariates.Covariate;
+import ca.joeltherrien.randomforest.covariates.FactorCovariate;
+import ca.joeltherrien.randomforest.covariates.NumericCovariate;
 import ca.joeltherrien.randomforest.regression.MeanResponseCombiner;
 import ca.joeltherrien.randomforest.regression.WeightedVarianceGroupDifferentiator;
 import ca.joeltherrien.randomforest.tree.Node;
@@ -13,7 +16,6 @@ import java.util.Map;
 import java.util.Random;
 import java.util.stream.Collectors;
 import java.util.stream.DoubleStream;
-import java.util.stream.Stream;
 
 public class TrainSingleTreeFactor {