The definition of subitize defined in Dictionary.reference.com is to perceive at a glance the number of items presented, the limit for humans being about seven.
This page http://gse.buffalo.edu/fas/clements/files/Subitizing.pdf tell “What is it? Why teach it?”
The following definitions and how to remember is from http://www.mathsisfun.com/numbers/cardinal-ordinal-nominal.html:
- A Cardinal Number is a number that says how many of somethig there are, such as one, two, three, four, five.
- A Cardinal Number answers the question "How Many?" It does not have fractions or decimals, as it is only used for counting.
- How to remember: "Cardinal is Counting"
- An Ordinal Number is a number that tells the
position of something in a list. 1st, 2nd, 3rd, 4th, 5th etc.
- How to remember: "Ordinal says what Order things are in".
- A Nominal Number is a number
used only as a name, or to identify something (not as an actual value or
- How to remember: "Nominal is a Name".
What have I learnt for this third session?
- Subitizing in Mathematics
- Reinforcement of cardinal, ordinal and nominal numbers
- Revisit what I learned as a student on subtraction using fractions.