Not sure how to teach subitizing? Keep reading for some helpful things to do, and things to avoid.
Subitizing. It’s a foundation for number sense and mental math. Students who can subitize have stronger math skills. So, what are some tips and tricks for teaching subitizing? Believe it or not, you can improve your students’ subitizing skills with a few simple routines. Keep reading to learn about common mistakes teachers make with subitizing – as well as how to teach subitizing effectively.
But first, let’s start with a critical question:
What does subitizing mean?
Subitizing is the ability to rapidly and automatically recognize a set of objects, without counting. When someone holds up 4 fingers, you don’t have to count them. You just know that there are 4. When you see 6 dots on a die, you know it’s 6.
There are two kinds of subitizing: perceptual and conceptual. Perceptual subitizing involves small sets. It precedes conceptual subitizing. Conceptual subitizing involves larger numbers and breaking them into smaller groups. For instance, when looking at 8 dots, you might see 4 and 4.
Subitizing is closely tied to number sense. Subitizing larger numbers helps students develop flexibility with numbers. This flexibility helps them see that numbers are composed different ways. For instance, 10 can be 4 and 6 or 3 and 7. This flexibility helps students become more efficient with mental math. Strong subitizing skills set students up for future success in math.
How do students develop subitizing skills?
Students develop subitizing skills by working with number sets – groups of objects, fingers etc. The secret is repeated practice with number sets. The practice can be brief, but should be fairly regular until students quickly recognize the quantity.
This quick practice can use the following strategies:
- building numbers in ten frames
- games – including any games with dice or dominoes
- subitizing flash cards
- number talks with the flash cards (especially with conceptual subitizing, so kids can explain the sub-groupings they saw)
If you aren’t familiar with subitizing flash cards (or quick flashes), you can learn more in this post.
Now that you know what subitizing is, be careful about the following common mistakes teachers make when teaching subitizing. Fixing these mistakes can really strengthen your students’ subitizing skills.
What are the most common mistakes when teaching subitizing?
- Using “Quick Images” that aren’t quick
- Using only one kind of image
- Accidentally encouraging counting
- Starting with too many numbers
- Only focusing on the answer
So, you might be wondering how to teach subitizing effectively… Here area few tips and tricks.
Keep “Quick Images” Quick
Quick images are a great way to teach subitizing. These are large flashcards with dot patterns (or other number sets, like ten frames or tally marks.) First, the teacher quickly shows the card. Then the students call out the number of dots on the card. (Learn more about using these subitizing cards in your room here.)
But quick images need to be quick! Be careful not to leave the cards up (visible to the students) too long. More than 2-3 seconds gives students time to count the dots. Remember, subitizing is recognizing the quantity without counting. Kids need to recognize these patterns quickly.
Are you new to subitizing cards, but don’t have time to make your own? I have a set of subitizing cards in my store that use ten-frames, dot patterns, dominoes, finger patterns and tally marks. All you have to do is print and they are ready to use! Grab them here!
Use Multiple Types of Images
Ten-frames are really popular. And they definitely help with subitizing. But, the whole point of subitizing is flexibility. If you only use ten-frames, your students will only be quick with ten-frames. But they may not quickly recognize patterns on dice or with fingers.
It’s important to expose students to a variety of images to subitize. Be sure to expose students to other patterns, such as dominoes, tally marks, and finger patterns.
Sometimes teachers accidentally encourage kids to count the images. You might use the word “count” when you mean “say the number.” For example:
- Count how many.
- Can you count to check?
You might also encourage counting by allowing too much time to respond. Remember, the goal is to recognize the quantity quickly, without counting. This is especially true with larger numbers. Instead of counting, encourage students to use what they already know. Breaking larger groups into smaller sets helps them subitize faster.
For instance, with the second card above, a child might quickly see a group of 2 and a group of 3. She may start with the 3 and count up 2 more, reaching 5. Using the counting on strategy is more efficient than counting all.
It is especially important to discourage counting during subitizing games, such as this subitizing war game. When playing with a partner, students are more likely to revert to counting objects, so it’s important to roam the room and coach kids for automaticity when needed.
Emphasize quick recognition of patterns. This leaves brain power for other parts of problem solving. It’s a similar process to reading. When students automatically recognize words, they can attend more to comprehension. Similarly, automatic recognition of patterns allows students to do some “mental gymnastics” to solve math problems. Being automatic from the beginning prepares students for mental math.
Start with just a few numbers
Don’t overwhelm students from the beginning. Instead, work with numbers to 4 or 5 first. This will help students develop perceptual subitizing skills. Once they have developed automaticity with these smaller number sets, work with numbers to 10.
As you move to larger numbers, start with patterns that make it easy to see combinations. This will allow students to use what they already know to identify larger number sets. Look at the card below. Once you recognize 3, it’s easier to recognize 6 as two sets of 3. Making the patterns easier to see helps encourage students to subitize, rather than count. They may need to start by seeing 3 and counting on. This is appropriate for larger numbers.
Focus on the Process
One final mistake when teaching subitizing is to focus solely on the answer. A quick answer (without explanation) is appropriate for numbers to 5. However, when you move to slightly larger numbers, it is important to have conversations about how students figured out the answer. For instance, when seeing the 6 dots above, one student might see it as a group of 4 and 2 more. Another child could see it as 3 on top and 3 on the bottom. This builds flexibility with numbers.
Fix those mistakes when teaching subitizing
Help your students develop strong subitizing skills by remembering these tips:
- Keep “Quick Images” quick
- Use multiple types of images
- Discourage counting
- Start with just a few numbers
- Focus on the process
By making small changes to your instruction, you will help your students become amazing mathematicians. Their strong subitizing skills will help them mentally solve math problems with ease.
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