Challenge 1 — Solution

Task: Write an if/elseif/else chain that takes a temperature in Celsius
(use a variable, try a few different values) and echoes "Freezing",
"Cold", "Mild", or "Hot" based on reasonable thresholds you choose
yourself.

<?php
    $temperature = 8;

    if ($temperature < 0) {
        echo "Freezing";
    } elseif ($temperature < 10) {
        echo "Cold";
    } elseif ($temperature < 20) {
        echo "Mild";
    } else {
        echo "Hot";
    }
?>


Output (for $temperature = 8):
Cold

Notes:
- Each threshold is checked in order - since 8 is not less than 0, PHP
  moves on to the next condition, where 8 < 10 is true, so "Cold" is
  echoed and every remaining elseif/else is skipped.
- Try setting $temperature to -5, 15, and 25 to see each of the other
  three branches run instead.
- The exact threshold values are a judgement call - what matters is
  that each range is checked in a sensible order and the chain covers
  every possible temperature with no gaps.