Students play. Teacher present s. Class discussion. Opening. Closing. Copyright min. min. min. min. min

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1 1 U n t er r ich t splan Ad d ing and Subtracting on the Number Line Altersgruppe: Ye ar 2, Ye ar 3 The Australian Curriculum: ACM N A013, ACM N A03 0 NSW Mathematics K-10 Syllabus: M A1-5 N A, M A1-5 N A. Victorian Curriculum: VCM N A107 NSW Numeracy Continuum K-10: 2.A 2.2 Online-Ressourcen: T o e t he Li ne Opening Teacher present s Students play Class discussion Closing ZIELE: E xpe ri e nc e an interactive number line P rac t i c e moving along the number line to add and subtract Learn to identify values on a number line De vel o p algebra skills

2 2 Ope ni ng 5 Display the following question and number line. Have the students write their answers in their notebooks. What is wrong with this number line? When the students are done writing, share. What is wrong with the number line? The number line should have arrows on either end. It is numbered incorrectly. The numbers must go up consistently, like this: or this: Today, we re going to look at some number lines. Pay attention to how they are numbered, and remember that the numbering needs to be consistent. T e ac he r prese nt s T o e t he Li ne 12 Present Matific s episode T o e t he Li ne - Addi ng and Subt rac t i ng o n t he N umbe r Li ne to the class, using the

3 3 projector. The goal of the episode is to fill in missing numbers on a number line.some questions will require you to add or subtract. Example : Please read the instruction. Place the tags correctly on the number line. We should always be aware of the intervals on the number line. What are we counting by? Each tick mark represents 1. How can we detere where to place the tags? Some tags we can place simply by counting. Others, we need to either calculate first, or we need to find the starting place on the number line and move forward or backwards, as the tag indicates. Ask the students to place the tags. Enter the students answers, and click on. If the answer is correct, the episode will proceed to the next question. If the answer is incorrect, the instructions will wiggle and the incorrect tags will wiggle and fall from the number line. The episode will present a total of six problems.

4 4 St ude nt s pl ay T o e t he Li ne 12 Have the students play T o e t he Li ne - Addi ng and Subt rac t i ng o n t he N umbe r Li ne on their personal devices. Circulate, answering questions as necessary. Cl ass di sc ussi o n 14 Display the following: Hand each student two sticky notes. Ask them to pick a number between 0 and 15. On each sticky note, they should write instructions for how to land on that number. One sticky note should include the word before and one should include the word after. For example, if the number selected is 8, we could write 3 steps after 5 and 6 steps before 14. Ask the students to come forward a few at a time to place their sticky notes above the correct number on the number line. They should place one note above the other. We found different ways to arrive at the same number. One required addition, and the other required subtraction. Now I m going to give you a starting number and an ending number. You need to state two steps that will take us from the starting number to the ending number. For example, let s say the starting number is 3 and the ending number is 9. Your two steps could be: 1) move forward 7, and 2) move back 1. The starting number is 7 and the ending number is 14. What are your two steps?

5 5 A possible response: Move forward 6 and then move forward 1. Is that the only solution? No, there are infinite ways to get from 7 to 14. State another way. A possible response: Move forward 10 and then move back 3. The starting number is 2 and the ending number is 10. What are your two steps? A possible response: Move forward 3 and then move forward 5. Solicit a few more possible responses. The starting number is 12 and the ending number is 8. What are your two steps? A possible response: Move back 2 and then move back 2 again. Solicit a few more possible responses. Now I ll give you the ending number and the one step we took to get there. You need to detere the starting number. The ending number is 13 and we moved forward 5 to get there. At what number did we start? How do you know? We started at 8. This is because if we moved forward 5 and landed on 13, we can work backwards by starting at 13 and moving the opposite direction (backwards) 5. Five spots back from 13 is 8. The ending number is 7 and we moved back 2 spaces to get there. At what number did we start? We started at 9. If we move back 2 spaces from 9, we arrive at 7. The ending number is 11 and we moved forward 4 spaces to arrive at 11. At what number did we start? We started at 7. If we start at 7 and move forward 4 spaces, we arrive at 11. Continue asking questions of this nature until you are confident that the students can easily solve them.

6 6 Cl o si ng 4 Display the following: Which tag does not belong? How do you know? The tag on the right does not belong. The first two tags are equal to 11; the final tag is equal to 13. Display the following: Which tag does not belong? How do you know? The tag in the middle does not belong because it equals 11 and the other two equal 15. Have the students work in pairs. Each student should write three tags, two of which are equal, and then exchange papers with his partner. Each student should exae his partner s three tags to detere which tag does not belong.

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