Day 28: Multiplying Decimals

6th Grade Math Standards: 6.NS.3 Fluently add, subtract, multiply, and divide multi-digit decimals using the standard algorithm for each operation.

Objective: Multiply decimals to find a product; justify the answer to a multiplication of decimals problem in a real-world and mathematical context

Agenda:

1. Visual Pattern #16
2. QSSQ
3. Review Homework
4. Multiplication of Decimals My Favorite No
5. Multiplication of Decimal Notes or students who mastered it already could do the Yummy Math NBA Best Player with a partner
6. Multiplication of Decimals Practice 

Assessment: My favorite no was assessed to see what students would come up with for an estimate to the problem 4.2 x 8.53. I asked students to first write a number that did not make sense for a product. Then I told them to write an answer that would make sense, but not do any calculations. They come up from fifth grade either without the skill or they simply rehearse that the decimal point needs to slide. I want them to have the number sense to be able to check their answers quickly and see if the answer makes sense or not. I have also found in the past that some kids cannot memorize the rule of sliding the decimal over, so my strategy was to have students put an estimate in as a way of making sense of their answers.

Glass Half-Full: I crossed out many of the problems students needed to do on the homework and instead told them to put in an estimate on the problems that they did have to do which was about seven problems in each class. I wanted the idea of estimating to be drilled in because students have a hard time doing this on their own for whatever reason - perhaps it is perceived as more work. To me though this skill (making sense of the answer) is the most essential part of multiplying decimals because it is apparent that they will have the tools to calculate these problems in their pockets anyway, but that will not save them from knowing when and knowing why. That is what needs to be built in.

Regrets: This is good effort. I think.

Visual patterns are designed to teach students that they can do this, but should look for an alternative. The student who did this was really proud and asked if I wanted her to finish at home since I took a picture of it. I said she was nuts.

Link: Lessons from Illuminations.