adding messenger project

docs/projects/messenger.md

@@ -0,0 +1,65 @@
+# messenger
+
+![](/static/mb/projects/a9-radio.png)
+
+Use the radio to create an app that sends "YO" messages.
+
+## Step 1
+
+Use [on button pressed](/reference/input/on-button-pressed) to send the number "0" over radio.
+
+```blocks
+input.onButtonPressed(Button.A, () => {
+    radio.sendNumber(0);
+});
+```
+
+## Step 2
+
+Use [radio on data received](/reference/radio/on-data-received) display "YO" when the number ``0`` is received
+by radio.
+
+```blocks
+let message = 0;
+radio.onDataReceived(() => {
+    message = radio.receivedNumber();
+    if (message == 0) {
+        basic.showString("YO")
+    }
+})
+```
+
+Compile the program and **upload the same .hex file to 2 devices!**
+
+## Step 3
+
+Use [on button pressed](/reference/input/on-button-pressed) to send the number "1" over radio.
+
+```blocks
+input.onButtonPressed(Button.B, () => {
+    radio.sendNumber(1);
+});
+```
+
+## Step 4
+
+Add blocks in [radio on data received](/reference/radio/on-data-received) to display "BYE" when the number ``1`` is received
+by radio.
+
+```blocks
+let message = 0;
+radio.onDataReceived(() => {
+    message = radio.receivedNumber();
+    if (message == 0) {
+        basic.showString("YO")
+    }
+    if (message == 1) {
+        basic.showString("BYE")
+    }
+})
+```
+
+
+```package
+microbit-radio
+```

docs/projects/telegraph-challenges.md

@@ -1,12 +1,12 @@
 # telegraph activity 
 
-Build a telgraph.
+Build a telegraph.
 
 # micro:bit telegraph
 
 Have you ever tried to communicate through a telegraph? Let's try coding a "Telegraph" on two BBC micro:bits !
 
-Complete the following [guided tutorial](/projects/telegraph), your hack should look like this:
+Complete the following [tutorial](/projects/telegraph), your hack should look like this:
 
 ![](/static/mb/lessons/telegraph-0.png)