diff --git a/src/playfield.rs b/src/playfield.rs
index 99f7d54..5027262 100644
--- a/src/playfield.rs
+++ b/src/playfield.rs
@@ -22,7 +22,6 @@ impl Playfield {
 
         playfield
     }
-
     fn parse(&mut self, field: &String) {
         let chars = field.split(" ").collect::<Vec<&str>>();
 
@@ -53,6 +52,9 @@ impl Playfield {
             }
         }
     }
+    pub fn get_column(&self, index: usize) -> Vec<Field> {
+        Vec::new()
+    }
 }
 
 impl fmt::Display for Playfield {
@@ -97,6 +99,24 @@ mod tests {
         }
     }
 
+    mod get_column {
+        use super::*;
+        #[test]
+        fn simple() {
+            let playfield = Playfield::new(&"1 2 3 1 2 3 1 2 3".to_string(), 3);
+            let expected_1 = vec![Field::new(1); 3];
+            let expected_2 = vec![Field::new(2); 3];
+            let expected_3 = vec![Field::new(3); 3];
+
+            let column_1 = playfield.get_column(1);
+            let column_2 = playfield.get_column(2);
+            let column_3 = playfield.get_column(3);
+
+            assert_eq!(column_1, expected_1);
+            assert_eq!(column_2, expected_2);
+            assert_eq!(column_3, expected_3);
+        }
+    }
     mod parse {
         use super::super::*;
 
@@ -116,7 +136,7 @@ mod tests {
                         vec![Field::default(), Field::default(), Field::default()],
                         vec![Field::new(3), Field::new(2), Field::new(1)]
                     ],
-                    open_fields: vec![]
+                    open_fields: vec![3, 4, 5]
                 }
             )
         }
diff --git a/src/sudoku_solver.rs b/src/sudoku_solver.rs
index d72cc7b..adc56ca 100644
--- a/src/sudoku_solver.rs
+++ b/src/sudoku_solver.rs
@@ -17,25 +17,35 @@ impl SudokuSolver {
         return self.playfield.clone();
     }
 
-    fn populate_possible_values(&self) {
-        for open_field in &self.playfield.open_fields {}
-    }
-    fn possible_values_from_row(&self, row: &Vec<Field>) -> Vec<u32> {
-        let max_value = self.playfield.size as u32;
-        let possible_values: HashSet<u32> = (1..max_value + 1).collect();
+    fn populate_possible_values(&mut self) {
+        for open_field in &self.playfield.open_fields {
+            let row_index = open_field / self.playfield.size;
+            let row = &mut self.playfield.fields[row_index];
+            let col_index = open_field % self.playfield.size;
 
-        let populated_values: HashSet<u32> = row
-            .iter()
-            .filter(|field| field.value.is_some())
-            .map(|v| v.value.unwrap())
-            .collect();
+            let possible_values = possible_values_from_row(row, self.playfield.size as u32);
 
-        possible_values
-            .symmetric_difference(&populated_values)
-            .map(|v| *v)
-            .collect()
+            let field = &mut row[col_index];
+            field.possible_values = possible_values;
+        }
     }
 }
+
+fn possible_values_from_row(row: &Vec<Field>, max_value: u32) -> Vec<u32> {
+    let possible_values: HashSet<u32> = (1..max_value + 1).collect();
+
+    let populated_values: HashSet<u32> = row
+        .iter()
+        .filter(|field| field.value.is_some())
+        .map(|v| v.value.unwrap())
+        .collect();
+
+    possible_values
+        .symmetric_difference(&populated_values)
+        .map(|v| *v)
+        .collect()
+}
+
 #[cfg(test)]
 mod tests {
     use crate::sudoku_solver::SudokuSolver;
@@ -53,36 +63,59 @@ mod tests {
 
         #[test]
         fn simple() {
-            let solver = setup_solver("1 2 3 2 3 1 3 1 0", 3);
-            let expected = create_test_playfield("1 2 3 2 3 1 3 1 2", 3);
+            let solver = setup_solver("1 0 3 4 4 0 2 0 0 1 0 2 2 4 0 3", 4);
+            let expected = create_test_playfield("1 2 3 4 4 3 2 1 3 1 4 2 2 4 1 3", 4);
 
             let solved = solver.solve();
 
             assert_eq!(solved, expected);
         }
     }
-    mod populate_possible_values {
-        mod possible_values_from_row {
-            use super::super::*;
+    mod possible_values {
+        use super::*;
+        #[test]
+        fn simple() {
+            let solver = &mut setup_solver("1 0 0 3 0 0 2 3 1", 3);
+            let expected_1 = vec![2, 3];
+            let expected_2 = vec![2, 3];
+            let expected_3 = vec![1, 2];
+            let expected_4 = vec![1, 2];
 
-            #[test]
-            fn simple() {
-                let solver = setup_solver("1 2 0 3 0 0 0 0 0", 3);
-                let expected_row_1 = vec![3];
-                let expected_row_2 = vec![1, 2];
-                let expected_row_3 = vec![1, 2, 3];
+            solver.populate_possible_values();
 
-                let possible_values_row_1 =
-                    solver.possible_values_from_row(&solver.playfield.fields[0]);
-                let possible_values_row_2 =
-                    solver.possible_values_from_row(&solver.playfield.fields[1]);
-                let possible_values_row_3 =
-                    solver.possible_values_from_row(&solver.playfield.fields[2]);
+            let field_1_values = &solver.playfield.fields[0][1].possible_values;
+            let field_2_values = &solver.playfield.fields[0][2].possible_values;
+            let field_3_values = &solver.playfield.fields[1][1].possible_values;
+            let field_4_values = &solver.playfield.fields[1][2].possible_values;
 
-                assert_eq!(possible_values_row_1, expected_row_1);
-                assert_eq!(possible_values_row_2, expected_row_2);
-                assert_eq!(possible_values_row_3, expected_row_3);
-            }
+            assert!(field_1_values.iter().all(|i| expected_1.contains(i)));
+            assert!(field_2_values.iter().all(|i| expected_2.contains(i)));
+            assert!(field_3_values.iter().all(|i| expected_3.contains(i)));
+            assert!(field_4_values.iter().all(|i| expected_4.contains(i)));
+        }
+    }
+    mod possible_values_from_row {
+        use super::super::*;
+        use super::*;
+
+        #[test]
+        fn simple() {
+            let playfield = create_test_playfield("1 2 0 3 0 0 0 0 0", 3);
+            let expected_row_1 = vec![3];
+            let expected_row_2 = vec![1, 2];
+            let expected_row_3 = vec![1, 2, 3];
+
+            let possible_values_row_1 = possible_values_from_row(&playfield.fields[0], 3);
+            let possible_values_row_2 = possible_values_from_row(&playfield.fields[1], 3);
+            let possible_values_row_3 = possible_values_from_row(&playfield.fields[2], 3);
+
+            assert_eq!(possible_values_row_1, expected_row_1);
+            assert!(possible_values_row_2
+                .iter()
+                .all(|item| expected_row_2.contains(item)));
+            assert!(possible_values_row_3
+                .iter()
+                .all(|item| expected_row_3.contains(item)));
         }
     }
 }