Beginning Subtraction

Procedure

Day 1:

Anticipatory Set:

Review number sentences with children (which they have been using in addition) to activate their memory.
Review the (+) sign and the (=) sign with the students à Write them on the white board and ask students if they can identify what each sign is. The students can look at the “important math terms” poster (Appendix F) that is hanging above the table.
Explain that they will be continuing to work with number sentences but will be starting a new topic. Write the new sign on the board (-). Ask if anybody already knows what this signs is used for.

Model/ Demonstration:

Introduce the (-) sign to the students. Explain that it is used when subtracting and is called a minus sign.
Introduce some vocabulary that they might hear when they are or should be using the (-) sign à subtract, less than, take away, minus, how many are left, etc.
Demonstrate subtraction, using marbles as a manipulative. Put five marbles on the table. Tell the students you are going to subtract (or take away) two. Count how many are left. All of the students should be able to answer and number question that you may ask from this problem because they are numbers that they can all recognize.
Write an empty number sentence on the whiteboard. Ask the students to help fill in the empty slots.

How many marbles How many marbles did How many marbles
did we start with? we take away? are left?

______________ - ___________________ = ___________________________

Guided Practice:

The teacher takes out the Cheerios that the students will be working with. She puts a handful on each of the student’s napkin. The students are told not to eat any of the Cheerios until they are told to. The teacher also passes out the addition/subtraction mats and dry erase markers.
The students are told to find the side of the mat that has the new subtraction sign that was just learned.
The teacher asks the students to count out a certain amount of cheerios (depending on the level of the group) and put them in the first spot. Then, the teacher tells the students to use their dry erase marker and write the number told in the second spot. This will be the number they are subtracting (eating). The students are prompted to eat the proper amount and count the remaining to Cheerios to find the answer.
As a group, the teacher and students fill in the number sentence with dry erase markers, at the bottom of the subtraction mat, which corresponds with the work they just finished (Appendix G).

Independent Practice:

The teacher continues to give students initial numbers and subtracting numbers to complete their subtraction sentences.
Since the students are familiar with number sentences, they should fill in their number sentences independently (with limited guidance for the lower groups)

Closure:

The students are asked to read their last number sentence, using the correct names for numbers and mathematical signs.

Assessment:

The teacher uses the informal observation checklist to gauge the knowledge and abilities of the students. If the teacher finds it necessary, she can write down the names of children that need to review the basics before moving on to the next lesson.
The students are assessed based on their ability to recognize and accurately write the necessary components in a number sentence.

Day 2:

Anticipatory Set:

Review with students the operation signs that are seen in subtraction number sentences.
Call on students to come to the board to write the symbols, call on other students to identify the symbols.

Model/Demonstration:

Using the white board, introduce another approach to solving subtraction problemsàthe crossing out method.
Draw a certain number (depending on the level of the group) of circles on the white board. Have a student count the number of circles, and then explain to the students that this is the initial number that we are going to start with. Cross out a few of the objects. Explain that when we cross the circles off, we are subtracting them from the group; this is the second number in the equation. Count how many are left; this is the answer.

Guided Practice:

The teacher passes out the pre-made dotted worksheets (Appendix H) to each of the students. The teacher completes at least the first of the worksheets with the group.
The students count how many dots are on the worksheet and put that number in the correct number slot in the number sentence (first slot). They then roll the dice. The number that appears on the dice is the number of dots that they will be crossing out; they also write this number in the correct number slot in the number sentence (second slot). The students then count the remaining dots and put the answer in the correct number slot in the number sentence (third slot).
Since the groups are small, the teacher is able to observe and guide each child as they are completing the activity. Because they are each rolling their own dice, the subtraction equations are going to vary.

Independent Practice:

There are at least 5 different pre-made dotted worksheets for each of the students to use. As they become more confident and comfortable with the activity, they can work more independently to complete each of the worksheets.

Closure:

In the last few minutes of the session, the students pair up and read their subtraction number sentences to a friend. This helps them become rehearsed with the vocabulary for this topic.

Assessment:

As the teacher is observing the students complete their work, she provides immediate verbal feedback. She praises or guides the students as they are crossing out and filling in their appropriate numbers. The teacher also provides verbal feedback as the students are communicating their number sentences to one another, at the end of the session.

Day 3:

Anticipatory Set:

The teacher asks the students what the symbol is called that we use when doing subtraction problems.
Then, the teacher takes down the “important math terms” poster (Appendix F) and they add the new term to the list.

Model/ Demonstration:

The students will be illustrating and crossing off their own illustrations to create subtraction problems.
The teacher verbally prompts the students with a story problem (varies depending on the level of the group) and ask them to illustrate the subtraction problem, as well as write a number sentence.
The teacher does one on the white board, in front of the entire group, so that the students can see the expectations. The teacher draws objects and fills that number in on the number sentence, crosses out the appropriate amount of objects and fills that number in on the number sentence, and counts how many are left and fills that number in on the number sentence.

Guided Practice:

The teacher completes another problem on the white board. She reads the story problem aloud and asks the students what it is that she needs to do. This is a group approach to writing and solving the problem.

Independent Practice:

The students complete a subtraction illustration and number sentence independently, from the story the teacher reads (Appendix J)
The students are given a blank sheet of paper with a number sentence along the bottom. The teacher reads aloud a subtraction story problem for the students to illustrate. The students are expected to draw the initial amount of objects, cross off the proper amount, and fill in the number sentence accordingly (Appendix I) .

Closure:

After completing the subtraction equation illustration and number sentence, the students assess themselves using their checklist. This gives them the chance to check their work and make sure that they have completed everything. It forces them to be honest with themselves if they do not want to go back and change any of the mistakes they may find.

Assessment: