Schema Markup Warnings (Teaches, warninghasCourseInstance, warningoffers)

Question

I want help about a schema markup that i wrote.

More specifically i wrote a schema on jason for a website that occupy with english lessons (hybrid). The majority of the code it was accepted. However i vae three warning. The first concern "Teaches". The code was that downbelow:

"teaches": "text",

another warning

"hasCourseInstance": [
    {
      "@type": "CourseInstance",
      "name": "LRN",
      "courseMode": "Online",
      "location": "gfgfgfgj 67"
    }

Another warning 

 "offers": {
    "category": "Thing",
    "@type": "Offer",
    "price": "450.00",
    "priceCurrency": "EUR"
    },

---

If someone have an advice about the above it will be very valuable for me.Thanks for advance.

I tried to follow schema.org documenation but i think i made mistake or isn't working well for me.