Task
Materials: number cards 1–10 and 10–20.
Oneonone with a student, the teacher shows the numbers 1–10, one number at a time, in random order. The teacher asks, “what number is this?"
If a student is not able to identify all the numbers 1–10, there is no need to continue with the teen numbers; the area for instruction is identified. The number shown and the student's responses to that number should be recorded: hesitations, subvocal counting, false starts, and errors. This information determines numbers the student knows, numbers the student almost knows, and numbers the student does not know, and can be used to inform decisions about emphasis during instruction.
If a student is able to identify all of the numbers 1–10 correctly and without hesitation the teacher should repeat the same steps using the number cards 11–20. Again, record successes, hesitations, and errors in order to target instruction.
IM Commentary
Students should be able to identify numbers when shown them in random order. If the numbers are shown in sequence then knowledge of the sequence supports identification, so correct identification does not necessarily indicate facility with reading numbers.
A long pause when identifying a number may indicate that a student is counting in order to get a sort of running start to help identify a target number. The student may use subvocal counting (like counting under their breath) from another number to arrive at the correct number name. This is a common student strategy that should be noted as this indicates that additional practice with this number is needed before they can be considered fluent.
There are other ways to check for number recognition. After laying out the cards 1–10 in random order the teacher can:

Ask, "Where is the 6?" and have the student point it out.

Point to a number and ask, “What number is this?”
The second of these two approaches is more difficult and suggests a more sophisticated understanding of number recognition. In the first, the teacher has supplied the number name and the student has only to recognize the numeral. In the second, the student must recall the number name.
Two pairs of numbers that are commonly confused are (a) 6 and 9 and (b) 6 and 8. If the student does not correctly identify (recall) a randomly presented number, it may be useful to repose the question so that is only necessary for the student to recognize it. (For example, quickly turn several of the number cards, including the problem number, face up and ask, "Where is the 8?")
Common confusions for numbers 11–20 include confusing 12 with 20 or with 21; identifying thirteen as “threeteen”, or fifteen as “fiveteen”; and confusing teen numbers from (13 to 19) with decade numbers (30 to 90).