diff --git a/07week/ticTacToe/package.json b/07week/ticTacToe/package.json
new file mode 100644
index 000000000..0db3279e4
--- /dev/null
+++ b/07week/ticTacToe/package.json
@@ -0,0 +1,3 @@
+{
+
+}
diff --git a/07week/ticTacToe/script.js b/07week/ticTacToe/script.js
index d0bc4bd52..d49480e75 100644
--- a/07week/ticTacToe/script.js
+++ b/07week/ticTacToe/script.js
@@ -1,27 +1,66 @@
 'use strict';
 
+function Square(props) {
+  return (
+    <button className="square" onClick={props.onClick}>
+      {props.value}
+    </button>
+  )
+}
+
 class TicTacToe extends React.Component {
   constructor(props) {
     super(props);
+    this.state = {
+      squares: Array(9).fill(null),
+      xIsNext: true,
+    }
+  }
+
+  renderSquare(i) {
+    return (
+      <Square value={this.state.squares[i]}
+      onClick={() => this.handleClick(i)}
+      />
+    )
   }
 
+  handleClick(i) {
+    const squares = this.state.squares.slice();
+
+    if( calculateWinner(squares) || squares[i] ) return;
+
+    squares[i] = this.state.xIsNext ? 'X' : 'O';
+    this.setState({
+      squares: squares,
+      xIsNext: !this.state.xIsNext,
+    });
+  }
+  
   render() {
+
+    let winner = calculateWinner(this.state.squares);
+    let status;
+    if(winner) status = 'Winner: ' + winner;
+    else status = 'Next player: ' + (this.state.xIsNext ? 'X' : 'O')
     return (
       <div>
+        <div className="status">{status}</div>
+        {/* <button className="reset" onClick={this.reset}>Reset</button> */}
         <div className="row">
-          <div data-cell="0"></div>
-          <div data-cell="1"></div>
-          <div data-cell="2"></div>
+          {this.renderSquare(0)}
+          {this.renderSquare(1)}
+          {this.renderSquare(2)}
         </div>
         <div className="row">
-          <div data-cell="3"></div>
-          <div data-cell="4"></div>
-          <div data-cell="5"></div>
+          {this.renderSquare(3)}
+          {this.renderSquare(4)}
+          {this.renderSquare(5)}
         </div>
         <div className="row">
-          <div data-cell="6"></div>
-          <div data-cell="7"></div>
-          <div data-cell="8"></div>
+          {this.renderSquare(6)}
+          {this.renderSquare(7)}
+          {this.renderSquare(8)}
         </div>
       </div>
     );
@@ -29,3 +68,23 @@ class TicTacToe extends React.Component {
 }
 
 ReactDOM.render(<TicTacToe />, document.getElementById('tic-tac-toe'));
+
+function calculateWinner(squares) {
+  const lines = [
+      [0, 1, 2],
+      [3, 4, 5],
+      [6, 7, 8],
+      [0, 3, 6],
+      [1, 4, 7],
+      [2, 5, 8],
+      [0, 4, 8],
+      [2, 4, 6]
+  ];
+  for( let i = 0; i < lines.length; i++ ) {
+      const [a, b, c] = lines[i];
+      if( squares[a] && squares[a] === squares[b] && squares[a] === squares[c] ) {
+          return squares[a];
+      }
+  }
+  return null;
+}
\ No newline at end of file
diff --git a/07week/ticTacToe/style.css b/07week/ticTacToe/style.css
index d550b6372..3d12600af 100644
--- a/07week/ticTacToe/style.css
+++ b/07week/ticTacToe/style.css
@@ -1,4 +1,16 @@
-div[data-cell] {
+body {
+  font-family: Arial, Helvetica, sans-serif;
+}
+
+.status {
+  width: 300px;
+  text-align: center;
+  margin-bottom: 5px;
+  font-size: 20pt;
+  font-weight: 600;
+}
+
+.square {
   width: 100px;
   height: 100px;
   background-color: #f2f2f2;
@@ -6,6 +18,7 @@ div[data-cell] {
   border: 1px solid #808080;
   font-size: 100px;
   text-align: center;
+  outline: none;
 }
 
 .row {