Create entity view block
Please follow the below steps. You will achieve what you have asked.

1. Go to Structures &gt; Views &gt; Add a New View (named Courses)&gt; Select Type as Courses &gt; Create a Block 

2. Enter the Block Title as Courses &gt; Continue and Edit

3.  Under the Advanced &gt; Add Relationships search for Entity Reference: Referencing entity (select the same field which was referenced under school content type) and click on apply

4. Under contextual filter &gt; Search and select Content: Nid and in relationship option select the relationship and under WHEN THE FILTER VALUE IS NOT AVAILABLE
 select as  Provide default value &gt; Content id from URL &gt; Click on apply

5.  And under format or Fields, you can select anything depending on how you want to display the data