The Problem: Yii2 utilizes by default UserIdentity configured in config/web.php for connection, this object appy one table to authentication ('identityClass' => 'app\painel\models\User'). How to authentication from diferent tables? Solution: Create instances in web.php to uses UserIdentify. eg:

  $user = \Yii::$app->user;  
  $school = \Yii::$app->school; 
  $teacher = \Yii::$app->teacher;

My config/web.php

     'user' => [
            'class'=>'yii\web\User',
            'identityClass' => 'app\models\User',
            'enableAutoLogin' => false,
            'authTimeout' => 60*30,
            'loginUrl' => ['dashboard/login'],
            'identityCookie' => [
                'name' => '_panelUser',
            ]
        ],
        'school'=>[
            'class'=>'yii\web\User',
            'identityClass' => 'app\models\SchoolUser',
            'enableAutoLogin' => false,
            'authTimeout' => 60*30,
            'loginUrl' => ['dashboard-school/login'],
            'identityCookie' => [
                'name' => '_panelSchool',
            ]
        ],
        'teacher'=>[
            'class'=>'yii\web\User',
            'identityClass' => 'app\models\TeacherUser',
            'enableAutoLogin' => false,
            'authTimeout' => 60*30,
            'loginUrl' => ['dashboard-teacher/login'],
            'identityCookie' => [
                'name' => '_painelTeacher',
            ]
        ],

Note for each there is a identifyClass and one view login. Now, we need to create the models:

namespace app\models;
use Yii;
// My user
class User extends \yii\db\ActiveRecord implements \yii\web\IdentityInterface
{
    public static function tableName()
    {
        return '{{%user}}';
    }
    //// to continues....

Model scholl:

namespace app\models;
use Yii;
// My School
class SchoolUser' extends \yii\db\ActiveRecord implements \yii\web\IdentityInterface
{
    public static function tableName()
    {
        return '{{%schoolUser}}';
    }
    //// to continues
    

Model Teacher:

namespace app\models;
use Yii;
// My School
class TeacherUser'' extends \yii\db\ActiveRecord implements \yii\web\IdentityInterface
{
    public static function tableName()
    {
        return '{{%teacher}}';
    }
    //// to continues....

Now In my example I want to have controllers for each type of access, without generating conflicts between them:

In Behavior of the controller i have defined for dashboard-school, teacher and user, the user object representing the authentication status or the ID of the user application component.

	//behaviors of the school
public function behaviors()
{

    return [
        'access' => [
            'class' => AccessControl::className(),
            'user'=>'school', // this user object defined in web.php
            'rules' => [
                [
                    'allow' => true,
                    'roles' => ['@'],
                ],
                [
                    'allow' => true,
                    'actions' => ['login'],                    
 'roles' => ['?'],

                ],
            ],
        ]
    ];
}

To use login:

//school
 \Yii::$app->scholl->login($model, $this->rememberMe ? 3600*24*30 : 0);

 //teacher
 \Yii::$app->teacher->login($model, $this->rememberMe ? 3600*24*30 : 0);

For restrict access in views:

<?php if (!\Yii::$app->scholl->isGuest):?>
<h1>My scholl Name: <?=\Yii::$app->scholl->identity->name?>
<?php endif;?>

<?php if (!\Yii::$app->teacher->isGuest):?>
<h1>Teacher Name: <?=\Yii::$app->teacher->identity->name?>
<?php endif;?>

Always use the specific instance of the user you want to work with.

Criticism, suggestions and improvements, use the comments