CSOs: M.O.1.1.11 model operations, addition and subtraction, and the relationship between addition and subtraction (e.g., identity element of addition, commutative property, fact families, and inverse operations) using concrete objects.
Learning Skills: 21C.O.PK-2.3.LS.1: Student manages negative emotions, aligns his/her goals to the goals of others, and works cooperatively and productively with others in small groups.
21C.O.PK-2.2.LS.2: Student identifies parts of a system and explains how those parts interact with one another.
21C.O.PK-2.3.LS.5: Student uses clearly defined teacher directions and interpersonal skills to move others toward the goal.
Tech Tools: 21C.O.PK-2.1.TT.7: Student, working in a teacher-led whole group project, uses presentation software to illustrate concepts and communicate ideas.
Launch/Introduction (suggested time 15-25 minutes)
Activating Prior Knowledge
Children should understand addition and subtraction. They should be able to add sums to 18 and subtract from 18 or less.
Review addition and subtraction facts with students.
Use an ELMO projection device and manipulatives, such as counters, to demonstrate addition and subtraction on the screen. Lay out the manipulatives and write the related fact underneath. Explain the number sentence.
Follow this process several times using addition and subtraction problems and explain the vocabulary terms that are associated with the number sentences.
End this mini-lesson with a review of the vocabulary terms. Write several number sentences under the ELMO and call out a term. Ask students to identify components of each sentence that represent the given term.
Students will dramatize addition and subtraction facts.
The teacher will model this process first.. Hand out two 8x10 pieces of paper, one with an addition sign and one with a subtraction sign and give each sign to a student to hold. Stand 8 other students in front of the class. Call out addition facts with sums of 8. Students divide themselves to physically show each addition fact. Example: given the fact 4+4, students divide themselves into two groups of 4 each, with the + sign standing between. Teacher may choose to have students also model the corresponding subtraction fact.
Teacher has students model other addition facts for 8….. (7,1) (6,2) (5,3), students rearranging themselves accordingly. Teacher may have students model the corresponding subtraction fact for each addition fact as it is dramatized.
Form the students into groups of five and let them practice dramatizing addition and subtraction facts using five people. Each group should have a set of papers with the + AND - signs on them. The students should be given time to discuss the question, “How are addition and subtraction related?”
Bring the students back together in the whole group. Allow groups to demonstrate their dramas to the class and explain what they discovered about the relationship between addition and subtraction.
The teacher will use an internet site to review math facts. You will need a projection device to project the internet up on the screen.(Students will be able to access this site on their own for additional practice.)
Investigate/Explore (suggested time varies from 30-40 minutes)Buddy Practice Activity 1
Students will “buddy up”. While sitting as a whole group on the carpet, students will turn to a buddy and sit, knees to knees. The teacher will give each group of buddies 10 dominoes. The buddies will use each domino to determine the 2 addition and 2 subtraction facts for the fact family represented on the domino. Buddies use a dry erase board and marker to write down the four number sentences for each domino so they can keep track of them They will also discuss how the addition and subtraction sentences are related.
* Special note- the teacher should model this process with a buddy several times before groups begin. An ELMO document camera can be used to project the dominoes during modeling. If this is not available, an overhead projector can be used with overhead dominoes.
* Buddy up- This is a process I use to pair students. My class knows it very well. I say, “Buddy Up” They turn to a neighbor and sit knees to knees with hands in laps. If someone doesn’t have a buddy they stand up and I will match them with someone quickly. When I say, “Buddy Down”, they return to sitting alone. You may use any pairing technique you wish.
Buddy 1: 3 + 4= 7
Buddy 2: 4 + 3= 7
Buddy 1: 7 – 4 =3
Buddy 2: 7 – 3 =4
Buddy Practice Activity 2
The teacher will demonstrate the use of fact triangles. (see illustration). The teacher will pass out pre-made fact triangles to each student. Each student will have the opportunity to practice using the fact triangle. The students will practice using these triangles by themselves. The teacher will circulate around the room to keep children on task and check for understanding. Students may practice by whispering the facts to themselves or to a partner, or by writing the number sentences.
On the teacher’s signal, the students will pass their triangle to the right. (It may be to your advantage to have students sit in a circle on the group rug.)Rotate the triangles around the room until you have had the opportunity to observe each child using them correctly.
Fact triangle illustration
+ , -
Fact triangle directions For addition: Place your thumb over the black dot, covering the 7. Add the remaining numbers. 4+3=7.
For subtraction: Place your thumb over any of the numbers without the black dot. To begin the subtraction, start with the number with the black dot. Subtract the number not covered by the thumb. 7-3=4
Summarize/Debrief the Lesson ( time 30-40 minutes)
Review the vocabulary words associated with this lesson with students. Students will “buddy up”. Call out the vocabulary words one at a time and have the buddies tell each other what it means. Be sure to tell them the correct answer.
Give the buddies 2 minutes to discuss the essential question: How are addition and subtraction related? Spend 5-7 minutes letting the buddies report out their discussions.
Review the domino activity or the fact triangle activity or both with students. Write examples on the board and allow the students to explain to you what to do.
Students will return to their desks. Give them a white sheet of paper. Instruct them on folding the paper to get four blocks. In each of the blocks have the students draw a fact triangle and write the numbers of a fact family in each corner. Students write the associated facts of the fact family. You may want to assess their comprehension of the fact triangle, circulate around the room to assist and observe
I would use the ELMO document camera to allow students to project their work and explain. You may also let them explain their work to a buddy or another adult. In either case, they should be able to verbally defend their drawings.
Addition and subtraction have an inverse relationship. The inverse relationship between addition and subtraction can be used to find subtraction facts. Every subtraction fact has a related addition fact.
Teacher modeling is key! With each activity the teacher should model at least 4 examples.