When we talk to children there are inevitably a lot of clues around us that may help the child understand what we are saying. In fact this is what helps the small child learn to talk. We point to something and say the name of it.
If we are trying to assess how much language a child understands then we have to try to take away the clues so that we are just looking at the child's understanding of the words alone. One way of doing this would be to have nothing around you at all of relevance to what you are saying. In this way the child is totally reliant on understanding the words of the instruction you give, as long as you don't give any nods of the head in the direction of anything relevant to the response, or any pointing with fingers or eyes.
Another way of taking away the clues is to think of language in terms of how many information-carrying-words are contained within a sentence.
For example: 'Give me the book'.
There are four words in this sentence but how many of these words would a child need to understand in order to carry out the instruction. This depends on how much of the information is 'redundant', in other words not needed at the time the instruction is given.
For instance, if the child is sitting at a table and there is just one book on the table in front of both of you, and you hold out your hand and look at the book while saying 'Give me the book' the child actually does not need to understand any of the words in the sentence to carry out the instruction: there are therefore then no information-carrying-words in the sentence on that occasion.
If there are two objects on the table, a book and a cup, and you hold out your hand, look at the book and say 'Give me the book' there are still no information-carrying-words in the sentence because you have provided all the clues the child needs to follow the instruction. However, if you don't look at the book then there is one information-carrying-word in the instruction. If you don't hold out your hand then there are two information-carrying-words in the sentence.
(NB: some of our language is redundant anyway and if you are the only other person in the room it is unlikely that the child would need to understand both give and me in order to follow the instruction appropriately in this particular example).
How to decide what level of understanding the child needs for any particular sentence.
In order for a word in a sentence to be considered to be an information-carrying word there must be an alternative choice for the child to select. In other words each information-carrying-word must have an alternative word that the child could choose.
Then the child will have to understand and remember all the ICWs in order to carry out the instruction fully. Any word which does not have a comparable alternative is not an ICW.
Some example activities:
1 ICW level
Where's the ball?
The intonation patterns used will normally be enough to signal to the child that this is a question. If not, gesture can be used to illustrate the general area where the child is expected to look, being careful not to point directly to the desired object or even to linger a little longer over it.
The objects on the table must include a ball and at least one other object.
2 ICW level
Put the ball on the table
The objects in front of you should include a ball and at least one other object and a table and somewhere else on which things can be placed. e.g.a chair.
The words 'put the' and 'on the' are really redundant in this sentence as the child can often assume the meaning of these from his previous experience.
3 ICWs
Make the big dolly jump.
Again, in this sentence the words 'make the' are redundant and cannot count as information-carrying-words.
To ensure a 3 word level of understanding here, you need two dollies: one big, one small, and you need a big and a small (teddy). The action can obviously be varied in this sentence.
4 ICWs
Give me the red cup and the blue teddy.
For this sentence you would need a red and a blue cup, and a red and a blue teddy.