<div id="search">
    <form name="search" action="index.php?page=2" method="get">
        <p>Search by:</p>
        <select name="criteria">
            <option>Name</option>
            <option>Last name</option>
            <option>Project name</option>
        </select>
        <br><input type="text" name="tern" placeholder="term">
        <br><button type="submit">Find`enter code here`</button>
        <hr>
    </form>
</div>

if(isset($_GET['page']) && $_GET['page'] == 2){
     include 'modules/search.php';
}