Subitizing is the ability to accurately and rapidly identify a small amount of items without having to count. It is immediately knowing what number is rolled on a six sided dice. Most adults don’t need to count the pips. The number comes automatically because the brain can subitize. Take a quick test at subitizing.com to see how well you can do.
While subitizing may be a new word being passed around in mathematics educational research, it is not as recent a concept as some might think. Beginning near the turn of the 19th century, educators began promoting that simply counting did not demonstrate true understanding of number and its related quantity, but that subitizing did. This was supported by experts like Freeman who later in the first half of the century stated that subitizing focused on the whole of the number as well as its parts in it’s most basic units.
By the 1970’s, it was expected that most children could easily and naturally subitize because it happened so readily in their natural environment, however that was not, and is, not the case for all children. Educators, such as Fitzhugh, then realized that while some children could not count the specific units of a number, they could subitize the units making up small sets before them, thus supporting the notion that subitizing is a precursor to counting. This does seem to make sense, as even babies as young as six months, and even birds, have been found to have an ability to subitize. Doug Clements sites the example that a six month old baby may is shown two images at the same time, on of two dots and the other of three dots. Then, the baby hears three beats on the drum and his eyes move to the image in front of him with the three dots. Obviously, this baby is not literally counting 1-2-3, but discriminating between two quantity sets.
But a counter argument exits that children use subitizing more as a shortcut for counting (Beckwith and Restle 1966; Brownell1928; Silverman and Rose 1980). After repetitive practice students may no longer need the to count the pips on a dice, but can automatically recognize their value, thus demonstrating more of a form of rapid counting.
Researchers are still as odds as to whether or not subitizing is a skills than comes before counting, however it is understood among the educative community that subitizing is something that can be taught and has a strong positive impact on number sense skills, the most basic and foundational of all mathematical skills. While subitizing practice is still uncommon in some schools, more and more research is supporting its being taught, and even children as young as preschool age are capable of learning basic subitizing. The following are three activities to teach subitizing:
- Quick Dot Images-Use colored dot stickers to make a set of cards with a set number of dots on each card. For beginners, dots should follow the most easily recognized pattern, like the pattern of pips on dice. Beginners should also start with small numbers, nothing higher than five or six. Select a card and flash it before the students, showing them the image for no more than three seconds at most, preferably shorter. The goal is to recognize the set as quickly as possible without having to actually count.
- Quick Dot Images Look Alike– Play the same games as above, but instead of students calling out the number, have them use manipulatives to create the same set on their tray or desk.
- Concentration-Make a double set of cards and have students play the matching game concentration. If playing with young children, such as preschoolers through first grade, consider using number sets up to three, but in multiple color sets. This way, the students gets lots of practice with the smaller numbers without getting too frustrated with trying to differentiate the larger sets. Once near mastery is evident, larger numbers can be added, as well as less familiar configurations.
For further reading…What Is Subitizing? A Building Block For Successful Mathematics by Ken’s Math: Kids Math Education for Number Sense Subitizing by Wikipedia Subitizing by Teach Math