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## Begin With Buttons

Pre-K-2

In this unit, students use buttons to explore logical and numerical relationships. The unit begins with two lessons that focus on the two basic logical thinking skills, classification, and seriation, which are the foundation for understanding numbers and number relationships. These abilities in turn form the basis for understanding addition and subtraction.

In the next six lessons, students explore the relationships between numbers and model addition and subtraction sentences with buttons.

Students will explore the operations of addition and all three meanings of subtraction (take away, comparative, and missing addend). A set model is used for both operations.

### Button Trains

Pre-K-2
In this lesson, students describe order by using vocabulary such as before, after, and between. They also review and use both cardinal and ordinal numbers.

### Many Sets of Buttons

Pre-K-2
Students classify buttons and make disjoint and overlapping Venn diagrams. In an extension, they make and record linear patterns.

### How Many Buttons?

Pre-K-2
In this lesson, students review classification, make sets of a given number, explore relationships between numbers, and find numbers that are one more and one less than a given number. They apply their knowledge of classification as they play a game similar to bingo.

### More and More Buttons

Pre-K-2
Students use buttons to create, model, and record addition sentences. They also explore commutativity in addition contexts.

### Numbers Many Ways

Pre-K-2
Students work with subtraction at the intuitive level as they explore number families and ways to decompose numbers to 10. They will also identify members of fact families. (A fact family is a set of three [or two] numbers that can be related by addition and subtraction, for example: 7 = 4 + 3, 7 = 3 + 4, 7 - 4 = 3, and 7 - 3 = 4. When the number is a double, there are only two members of the fact family. An example would be 10 - 5 = 5, and 5 + 5 = 10.)

### Lost Buttons

Pre-K-2
In this lesson and the following one, students investigate subtraction more directly, beginning with the easier “take away” mode. They model “take away” subtraction with buttons and write subtraction sentences. They also work with the additive identity (0) as an addend and as a difference and find missing addends.

### Shirts Full of Buttons

Pre-K-2
Students explore subtraction in the comparative mode by answering questions of “How many more?” and “How many less?” as they match sets of buttons. They also make and discuss bar graphs based on the number of buttons they are wearing.

### Looking Back and Moving Forward

Pre-K-2
This final lesson of the unit reviews the work of the previous lessons through a variety of activity stations, one of which involves using an interactive graphing tool. Students model with buttons and record addition and subtraction.