C.2 Count backward from 120-0 with sequences
Counting Backward from 120 to 0
Counting backward builds number sense and helps students understand how numbers decrease in order. It supports the idea of subtraction and prepares students for solving number problems.
- Start at 120 and count backward by ones down to 0.
- Practice stopping at numbers such as 87 or 54 and continue counting backward until 0.
- Use a classroom chart or number line to point to each number as you count.
Encourage students to say numbers clearly and slowly as they count backward. Repetition helps strengthen confidence and fluency.
Using Number Lines for Backward Counting
A number line shows the order of numbers in reverse when counting backward. It helps students see the relationship between numbers and the concept of “before.”
- Ask: “What number comes before 100?” and find it on the number line.
- Show how 59 comes right before 58 as you move backward.
- Highlight key benchmarks such as 120, 100, 80, 60, 40, 20, and 0.
Have students create their own number lines up to 120. Ask them to trace backward steps with a finger or marker to make the sequence concrete and interactive.
Connecting Backward Counting with Subtraction
Each step backward on a number line represents subtracting one. Counting backward is a visual and verbal way to practice subtraction facts with numbers up to 120.
- Write subtraction equations while counting backward: 25 – 1 = 24, 24 – 1 = 23, and so on.
- Ask: “Take 1 away from 112.” Students say the answer and write the equation.
- Use objects such as cubes, buttons, or counters to remove one at a time while saying the new number.
Link backward counting to everyday situations. For example, crossing off days on a countdown calendar or finishing snacks one at a time makes subtraction meaningful.
Recognizing Backward Counting Patterns
Patterns help students count backward more fluently. Practicing skip-counting develops stronger number sense and prepares learners for future multiplication and division concepts.
- Count backward by 1s from 120 to 0.
- Count backward by 5s: 120, 115, 110, 105 … down to 0.
- Count backward by 10s: 120, 110, 100, 90, 80 … down to 0.
Circle every fifth or tenth number on the number line. This shows clear skip-counting patterns and helps students recognize the structure of numbers.
Building Fluency with Number Sequences
Practicing backward counting with different starting numbers strengthens understanding of number sequences. It helps students see how numbers are ordered and related.
- Start at 75 and count backward by ones until 60.
- Ask students to identify “What number comes just before 47?”
- Challenge students to fill in missing numbers: 120, 119, ___, 117, ___, 115.
Use fill-in-the-blank sequences or short backward counting exercises in daily routines. Consistent practice leads to automatic recall of number order.