Katherine Brou
Math
10.19.11
Objectives and Standards: • TCW learn the strategy of making 10 when adding numbers +9, +8, and +7. o
2.OA.2. Fluently add and subtract within 20 using mental strategies.
o
2.NBT.8. Mentally add 10 or 100 to a given number 100–900, and mentally subtract 10 or 100 from a given number 100–900.
Higher Level Thinking Questions • What does 9+4 equal? o Tell me how you solved that… how could you prove that using these materials? • What changes can you make to solve this problem? • What would happen if I moved this chip from here (4‐bottom) to here (9‐top)? • How can you apply this same strategy to this problem (7+5)? • How does this strategy help us? Lesson Procedure • “Today we will explore the making 10 strategy to will help you solve addition problems.” o Yesterday we explored a strategy… it was called “making 10s” • Introduce materials and state purpose/show how to use them. Hand out the materials. • Do an example: 9+4… (ask for the answer – then ask how it was solved) • Talk about how to solve the problem (9+5) using the strategy we are exploring today: show them how to move chips (use ELMO) and talk about how 9+5 ends up as/= 10+4. • Have the children do a few examples with you until feel like they fully understand: 9+6, 9+3, 9+8, 9+4, 9+7 to challenge have them do one on their own. • Now introduce the example 8+4… talk about how this can be solved…show them on ELMO. (how is it the same/different as the first examples?) • Have them do a few problems with you until they understand: 8+3, 8+6, 8+7, 8+4 • Now introduce the example 7+6… talk about how this can be solved using our strategy… how can we apply what we have been doing to this problem? Now introduce how the children will be able to work with their partner to practice this skill… explain how to do it (3 rounds: 1 – 9+ a #; 2 – 8+ a #; 3 – 7+ a #) – they pick a card and add that number to 9/8/7 – use the boards to help them solve and their partner must check their work – encourage your friends: congratulate when they get it right and help them figure out what needed to be different if they got it wrong • Walk around the room as the children play this game; make note of their levels/abilities • End lesson by discussing… how does this strategy help us…who can do this in their head… can anyone explain to me how to do it without using chips… Assessment • Teacher Observation of the student’s use of the strategy and whether or not it is mastered/understood – checklist/anecdotal notes •