Partial Products Method
Adding and Subtracting Decimals
Try this fun interactive activity at home with your students...Change the decimal places to '2' and reduce the columns to '3'.
Decimals
Using base 10 blocks to represent decimals
1 "flat" = the whole = 100 cubes
1 "cube" = 1/100 of the whole = .01
1 "long" = 10 cubes = 1/10 or 10/100 of the whole = .10
Today's lesson objectives:
Students will...
Use base-10 blocks to represent decimals through hundredths.
Read and write decimals through hundredths.
Compare and order decimals through hundredths.
Rename fractions with 100 in the denominator.
ALGEBRA!!!
Today, students solved "Open Sentences". An Open Sentence is a number sentence with a variable (unknown). For example: 5 * y = 40. What does y (variable) equal?
Students utilized various strategies to solve the Open Sentences. Most would divide: 40 / 5 = 8. Therefore, y = 8. Putting the answer in the number sentence to make sure it works: 5 * 8 = 40.
What's My Rule?
"What's My Rule?" activities employ a "Function Box". This box has a rule that is applied to the number that goes "in" it, which results in an "out" number. For example: if the Function Box's rule is +20, and 30 is put in, the result is 50 (30+20=50). Students then work to solve problems where they are given the "out" number and rule, but need to determine what went "in". Finally, they are given both "in" and "out" numbers and have to determine the Rule. The skills developed are a prerequisite for pre-algebra.
Trade-First Subtraction
Time for the students to teach the class! Four students had a chance to show the class how they would solve multi-digit addition problems using the partial-sum method.
Today (10/6), we discussed three ways to solve a multi-digit addition problem. We solved them using “traditional”, partial-sums, and column-addition methods. Students also learned to make a “ballpark estimate” (close, but easier answer) prior to solving the actual problem, as a way to check their answers.
The purpose is to give the students options and explain why we solve the problem the “traditional” way. If you consider place value – if you add the 8 and 4 in the problem below, you get 12 and 12 is made up of 1 ten and 2 ones. Therefore, you put a 2 in the one’s column and add 1 ten to the tens column. You didn’t “carry” a number anywhere.
Let your students experiment with the partial-sums and column-addition methods. They are truly individual learners and should find a process that works for them, not be forced to solve it “the way we are comfortable with”. If the homework is frustrating, stop! This is an introduction to these methods and it won’t be the last time they see them. Please see our classroom website for the entire lesson as it was completed and saved on our Smartboard. Click here to review the lesson. There are 11
slides.
Here is an example of how to solve 248 + 184 three different ways:
Ballpark Estimate
250 + 180 = 430 or 250 + 200 = 450
Traditional
1 1
2 4 8
+1 8 4
4 3 2
Partial-Sums
2 4 8
+1 8 4
3 0 0 (200 + 100)
1 2 0 (80 + 40)
1 2 (8 + 4)
4 3 2
Column-addition
Guess Vs. Estimate
Students discussed the difference between making a "quick" guess and an educated estimate.
Class Lesson September 23rd
Students used a variety of strategies to "name" a specified number.
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