The first time that I heard about number sense, I had no clue what it actually meant. We started using ten frames and then number bonds and then even more. After years of just following my curriculum, I decided to explore what number sense actually is. Number sense is a crucial aspect of mathematical understanding that encompasses various foundational skills and concepts related to numbers. Although the exact categorization of number sense can vary, I am going to dive deep into nine parts in this blog series.

- Mastering Math: Exploring the Secrets of Number Sense Success (that’s this post)

## What is Number Sense?

The simplest definition that I found for number sense is that it is the building blocks for all strands of math. This means a great deal to a preschool or kindergarten teacher. Number sense is extremely important for students to master. All strands of math going forward rely on students to have mastery of number sense. What exactly are the parts of number sense? There are 9 parts to number sense: subitizing, magnitude, counting, one-to-one correspondence, cardinality, hierarchical inclusion, part-part-whole, compensation, and unitizing.

## Subitizing

Subitizing is one of those words that I did not know when I first began teaching. It was introduced with a few different activities. Subitizing is the ability to instantly recognize and name small quantities without counting. It is a precursor to counting and plays a crucial role in developing number sense.

Subitizing actually has two parts: conceptual subitizing and perceptual subitizing. Conceptual subitizing is being able to recognize an amount immediately because they saw it in parts and totaled it. Perceptual subitizing is seeing a group and being able to “just know” without counting. An example of perceptual subitizing is seeing four and showing 4 fingers.

An activity that you can do to help build students’ skills with subitizing is something as simple as using fingers. Students can practice making numbers on their fingers quickly. Another idea is to use subitizing cards or quick images. Subitizing cards are cards that have different objects on them. The objects can be in different arrangements. Students will quickly look at the card and try to tell how many without counting. You can grab these quick image cards.

## Magnitude

Magnitude is the understanding of relative quantity and size. Developing magnitude skills involves the ability to compare numbers and identify their relative positions. This includes determining which number is larger, which is smaller, or if two numbers are equal. By understanding magnitude, individuals can grasp concepts such as greater than, less than, and equal to.

For example, a toddler may have magnitude slightly. If a person holds out two hands with candy in each hand, the toddler most likely will reach for the hand that has more. This is magnitude. The toddler may not be able to tell how many is in each hand or be able to count, but they know that one has more than the other.

Activities that involve ordering numbers, such as arranging them in ascending or descending order, help develop magnitude skills. This allows individuals to visually and conceptually understand the relative positions of numbers in a sequence. Comparing sets of objects or quantities, such as counting groups of items and identifying which group has more or fewer objects, also enhances magnitude skills. This helps individuals relate numerical concepts to real-world scenarios.

Magnitude skills are closely linked to the understanding of concepts like greater than, less than, and equal to. By developing an understanding of magnitude, individuals can interpret and use these comparison symbols (>, <, =) accurately. They can determine, for example, if one number is greater than another or if two numbers are equal in value.

## Counting

Counting is being able to orally count in sequence before they can do one-to-one correspondence. It is the process of systematically assigning a number to each object or item in a set. Counting helps us answer questions like, “How many?” and “How much?” and provides a way to represent and communicate numerical information.

The process of counting is simple. It involves a sequential process of assigning numbers to objects or events. It typically starts with the number “one” and proceeds in order, incrementing by one with each object counted. This process allows us to determine the quantity of a set and establish an order or sequence. Rote counting is the initial stage where children learn to recite numbers in order without understanding the meaning. They may be able to say the numbers correctly, but may not know what the value of each number is.

Counting during the day can occur during morning meet, while waiting in the hall for the restroom, as you line up, during calendar, with number songs, or during the math block. Students can practice counting as they work in pairs, groups or independently. Centers and math intervention are other times that students can practice counting.

## One-to-One Correspondence

One-to-one correspondence involves assigning a unique counting word or number to each object or event being counted. It ensures that each object is counted once and only once, without skipping or double-counting any items. Each count word corresponds to one and only one object in the set.

One-to-one correspondence is essential for accurate counting. It helps maintain a reliable counting sequence and ensures that every item in a set is accounted for. Without this skill, counting may be inaccurate or imprecise, leading to incorrect quantity determination.

When students are struggling with one-to-one correspondence, there are a few strategies that you can introduce to help them master this skill. Pointing and counting is one strategy. You can encourage children to point to or touch each object as they count. This physical connection helps establish the link between the object and the count word, reinforcing one-to-one correspondence.

Manipulatives can also be introduced to help students master this skill. Use manipulatives like beads, blocks, and teddy bears as children move or group the manipulatives while counting. This will ensure that each item is accounted for individually. You can also have students to sing while counting or use visual cues to help.

Want to grab what you need to get started? Get this math intervention set which is perfect for helping little learners master number sense.

Join us for the next part in this series.