Number relations is a huge understanding for kindergarteners – they need to know how the numbers fit together. They need to know what number will come next or what number came first, without having to count all the way to that number to figure it out. They need to one more and one less.
Before students are ready to know one more and one less, they need to have a strong and concrete understanding of the order of numbers. They get this from counting… a lot. Check out these blog posts to see how I support my students with their counting, number relationships, and teen numbers. They especially need practice counting backwards – since most of their counting will be counting forwards. My favorite game to practice this is called “Pop!” where students count up or down to a number, moving around the circle, until they arrive at the target number. The person who says the target number has to say “POP!” and then sit down. You keep playing until there is only one person remaining.
Strategies for One More and One Less
When doing any activities that involve stating one more and/or one less of a number, students need supports in place that they can use as they are needed.
When starting to target this concept, start with concrete objects that the students are asked to count and then add one more or take one away after they finish counting. See if they can continue their counting to the next number without having to start back at zero.
Once you start taking away the physical objects, one strategy that students might use to figure out the next number, or the number that came before, is to count on from zero or a comfortable number. This is a fine strategy at first, but we want students to learn that this strategy is not efficient – it will take a while.
From this strategy, we want to help students pick a closer number to start counting on from. For example, if we ask them what is one more than 21, we don’t want them starting to count from 0. It might be better to count on from 15, or even better to count on from 20.
Eventually, we want students to be so comfortable with their number relationships that if you give them any number, they could tell you the number that is one more and one less than your number. This doesn’t happen overnight. Students progress through different number ranges and move through these progressions with tools to support them.
Progressions of Understanding One More and One Less
The first number range that students should know one more and one less in is numbers zero to ten. After students have a solid understanding of the number order for zero to ten, they need to work on numbers ten to twenty, or teen numbers. Finally, they can work on numbers twenty to one hundred, with a special focus on what happens when the decades change.
It is important to have tools available for students, should they need support knowing what is one more and one less. These tools shouldn’t ever be required to be used, but simply be available. We don’t want students to depend on these tools, but rather use them to help them further their progression within this math concept.
I love to teach my students to use number lines. I have a bunch that go up to 30 and they can take these to help them with more and less. Another great tool to teach students about is a hundreds chart, especially when they are working with numbers to one hundred.
Students need to have a strong concept of number relationships and need to know one more and one less of any number. This is work that takes time, but with the right strategies and tools, students can progress in their understanding!