Grammar: gradable and non-gradable adjectives

These are excellent questions about adjectives and adverbs, Nilie, and they are not usually addressed until intermediate or upper intermediate levels (if you are into the Common European Framework, this area would be addressed in level B1).
Let’s look at gradable and non-gradable adjectives in turn briefly, then at the issue of adverbs. For those students you mention who need rules, here come the rules…

Gradable adjectives

Many adjectives describe qualities that can be measured in degrees, such as size, beauty, age, etc. These adjectives are often called gradable adjectives, because they can be used in comparative or superlative forms, or with grading adverbs such as very or extremely, to show that a person or thing has more or less of a particular quality. The following are some examples of common gradable adjectives used with grading adverbs:

Don’t talk to Jenny, she’s very angry.

Sorry, I can’t stop, I’m extremely busy.

I’m worried about Tom, he’s dreadfully unhappy.

This is a very important matter.

That slice of cake is rather big.

Non-gradable adjectives

Some adjectives describe qualities that are completely present or completely absent. They do not occur in comparative and superlative forms, and cannot be used with adverbs such as very or extremely, because we don’t usually imagine degrees of more or less of the quality being described. They are referred to as non-gradable adjectives. Non-gradable adjectives do sometimes occur with non-grading adverbs such as completely which emphasize the extent of the quality, e.g.:

The questions were completely impossible.

The food was absolutely superb.

Adjectives which identify something as belonging to a particular type, sometimes referred to as classifying adjectives, are also non-gradable:

The questions were completely impossible.

The food was absolutely superb.

Gradable and non-gradable

Note that, sometimes, confusion arises because some adjectives have both gradable and non-gradable senses with similar meanings e.g.:

She sounded slightly foreign.

He’s advising on foreign policy.

In the first example, foreign is gradable because it refers to a measurable quality, whereas in the second, foreign is non-gradable because it refers to a particular type (of policy).

Which adverb to use?

As a rule of thumb, the common grading adverbs extremely, very, rather, slightly and a bit, which emphasize degrees of a particular quality, don’t usually occur with non-gradable adjectives, since non-gradable adjectives identify a particular type or an absolute quality. Compare the following examples with non-gradable and gradable adjectives:

On the other hand, common non-grading adverbs such as completely, totally and absolutely, which emphasize absolute qualities, do not usually occur with gradable adjectives, since gradable adjectives describe qualities which can be measured in degrees. Compare the following examples with gradable and non-gradable adjectives:

One further important thing to remember is that the commonly used adverb really, and the adverbs fairly and pretty (an informal variant of fairly) are regularly used with both gradable and non-gradable adjectives, e.g.:

It’s a really interesting / fascinating class.

Teaching tips

How you can explain the difference? Here is one way of presenting the difference between the two.

1. Draw a diagonal line on the board and write the word cold next to it. Explain that cold is a gradable adjective. This means it can be measured. Something can be fairly cold, quite cold, very cold, extremely cold etc. Add these examples along the line as you explain. (If you think it’s more logical to have the line going downwards to represent the dropping temperature, then reverse the above). Other gradable adjectives include hot, rich, big, hungry.

Cold

extremely cold

very cold

cold

quite cold

fairly cold

2. Now write the word freezing on the board. Ask students where they would put it on the 'cold line' (probably next to, or above, extremely cold). Explain that freezing is a non-gradable adjective. You can’t make a line of different kinds of freezing, as it is already at the extreme of the cold line. But you can use adverbs that represent that extreme end of the line (like absolutely freezing, or completely freezing)

3. Other examples of non-gradable adjectives are furious, terrified, overjoyed (these represent extremes) or alive, correct (these represent absolutes – something is alive, or it isn’t).

Useful exercises

If you want to have your students practising this, an obvious starting point would be to ask them to decide which adjectives (from a list that you prepare) are gradable and which aren’t. However, this kind of exercise is easily forgotten by students over the long term (sometimes even before they walk out the door!). If I wanted to practise this with my students I would try a personalization activity something like the following:

1. Create a series of 'frames' like the following:

I would eat … only if I were ____ hungry.

The last time I was ____ unhappy was…

…makes me ____ furious.

I think the film… is ____ terrifying.

If I were ____ rich, I…

2. Write these on the board and ask students to complete the gaps with the word very or absolutely. Go through this together as a group, highlighting the different kinds of adjectives and the rules. (Answers: 3 and 4 are with absolutely, 1, 2 and 5 are with very.

3. Tell students to complete the sentences so that they are true for them. Do an example first with number one. I would eat frogs’ legs only if I were very hungry.

4. Tell students to work in pairs and tell each other their sentences. Do some feedback on this as a group. Note: you could be more imaginative with your sample sentences than I was and have them all based on a similar theme (on the theme of food, or sports, or school for example), using this exercise to review vocabulary of that theme.