Cardinality: Cardinality is about associating the number symbol (called a numeral) with quantity. Children can say the counting sequence but they need to also understand that the symbol 3 represents a quantity of 3 items. This concept is paramount and is a vital component for computational thinking.
Counting Backward: Counting backward refers to saying the counting sequence backwards. Kids count back when subtracting. Your child’s teacher may also call this Counting Down. Counting down or backwards is more difficult than counting up or counting forward. This is naturally less familiar than saying the counting sequence forward. When kids count back to subtract, they have to keep a few rules in mind.
- If they are counting backward and tracking on their fingers, do they include the start number in the count sequence? If so, they need to know that the number after the last number said is the answer.
- If they start the count sequence with the number after the start number, then the last number said is the answer. So lets think about 10-3. A child could say 10, put up 3 fingers and begin counting backward 3 by tracking on her fingers. She would say, “9, 8, 7” and the last number she says is the answer. If the child says 10 but also represents it on her fingers when tracking the 3 she is going to count back, she would say, “10, 9, 8” and then she would need to know that the next number in the sequence is the answer.
Both ways are fine but if you notice that your child is typically off by 1, it is likely that she is making an error with this strategy.
Counting Down: See the definition for Counting Backward.
Subitize: To quickly see and assign a quantity to a group of objects. Subitizing does not involve counting.