The lesson is only 20 minutes long, so I dont have much time. Im hoping to get the basics and a good number of examples, so the students can then go away and recognise adjectives.

start with examples of things such as ......'the cat ................on a wall'

and ask them to add adjectives to describe the cat and the wall

see how many different sentences they can come up with

i would use white boards to jot ideas down quickly and then share them orally

easy examples are colour and size but more interesting adjectives could be other ways to describe a cat etc

good luck

Use the book "Many Luscious Lollipops" by Ruth Heller. I've read it to many grade levels and kids pick up on it quickly.

This is impossible to answer. How old are your students? What level are they at? What's the lesson context? What do you mean by 'the basics'? Position of adjectives? Order of adjectives if there's more than one? You need a much clearer idea of what you are going to try to teach. E-mail me if you want and give me more details,and I'll try to suggest something.

When your students understand what a noun is they then need to know how to identify the noun. Adjectives describe a noun..

Start where your students are. Have a examples of nouns which you can use to exemplify this.
Imagine a child's game.
Imagine a crowd scene of 20 men.
Which man is my brother? The tall one.
Which tall one? The tall one who is overweight.
The tall shabby one etc etc. Don't at this poiunt get into the one with brown shoes as the adjective here describes the shoes
Students then learn that adjectives help us identify the noun. So when we write the more we use adjectives to describe the noun it is for readers to imagine or identify the noun or subject or our sentence or writing.
Good luck