put lessons back for Michael

docs/lessons/looper/challenges.md

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+# looper block challenges
+
+Coding challenges for the looper. 
+
+## Before we get started
+
+Complete the following guided activity:
+
+* [activity](/lessons/looper/activity)
+
+At the end of the activity, your code should look like this:
+
+
+```blocks
+for (let i = 0; i < 6; i++) {
+    basic.showNumber(i)
+    basic.pause(2000)
+}
+```
+
+### Challenge 1
+
+What if we want to count up to lucky number 7 instead? Let's do that by changing the ending value to `7` instead of `5`.
+
+
+```blocks
+for (let i = 0; i < 8; i++) {
+    basic.showNumber(i)
+    basic.pause(2000)
+}
+
+```
+
+* Run the program now to see your changes.
+
+### Challenge 2
+
+What about 9? Let's do that by changing the ending value to `9`.
+
+```blocks
+for (let i = 0; i < 10; i++) {
+    basic.showNumber(i)
+    basic.pause(2000)
+}
+
+
+```
+
+
+* Run your code to see the new counter.
+
+### Challenge 3
+
+Now let's start counting from `3` instead! Our for loop will always start at `0` so we simply add `3` to the `i` variable when passing it to `show number`.
+
+```blocks
+for (let i = 0; i < 10; i++) {
+    basic.showNumber(i+3)
+    basic.pause(2000)
+}
+
+
+```
+
+Run it on the simulator!
+
+### Challenge 4
+
+Now, let's **count down from 9**. Change the line `show number(i + 2, 150)` to `show number(9 - i, 150)`.
+
+```blocks
+for (let i = 0; i < 10; i++) {
+    basic.showNumber(9-i)
+    basic.pause(2000)
+}
+
+```
+
+
+* Run the code to make sure it is doing what is expected.
+
+### Challenge 5
+
+After counting down from `9` let's show the string `BOOOM`!
+