Subtraction

Louisa raises and sells angelfish. She has six fish tanks, each with the same number of angelfish. After selling one tank of fish this morning, she now has 40 fish in the remaining tanks.
 * [[file:Giovanny.doc]]CGI:**
 * Something Fishy!**

How many angelfish did Louisa have before the sale?

Check these questions first. We used some of them last week during addition so you may have already used them.

These are the same as the ones Johnette posted. I jsut reformatted them so that they had my kids names in them etc. I also added the three choices of numbers. Remember, we have to do the same problems, but we can tweak the names as that does not hcange the complexity of the problem.

Objective: **3.3 Number, operation, and quantitative reasoning. The student adds and subtracts to solve meaningful problems involving whole numbers.** 3.3A Model addition and subtraction using pictures, words, and numbers. 3.3B Select addition or subtraction and use the operation to solve problems involving whole numbers through 999.


 * Day 1: Use place value blocks to model subtraction.**

The same principles from addition can be used in three-digit subtraction, except that regrouping works in reverse. One ten becomes 10 ones when regrouped. One hundred becomes 10 tens. Use the base-ten blocks to illustrate regrouping tens in three-digit subtraction for the problem 262 − 137. (Note that this is the inverse operation of the addition problem above.) Show how to regroup 6 tens as 5 tens, 10 ones, making 12 ones. Then subtract the ones: 12 ones − 7 ones = 5 ones. Remind children that they must then subtract tens using 5 tens, since they regrouped a ten as 10 ones to subtract the ones. Subtract the tens: 5 tens − 3 tens = 2 tens, or 20. Subtract the hundreds to solve the problem: 262 − 137 = 125. Model this same method to illustrate regrouping hundreds to solve 325 - 153. Remind children that they can check their subtraction by using addition. Help them compare the subtraction to the addition problems you already did, making sure the numbers match.
 * [[image:http://www.eduplace.com/math/mw/background/2/12/graphics/ts_2_12_wi-3.gif width="140" height="73" caption="stacked equations"]] ||
 * stacked equations ||

Use the graph paper to model subtraction with and without regrouping in algorithems. Here are some activities to do:
 * Day 2: Practice subtraction using algorithems**



Make sure you spend PLENTY of time with this as our kids usually struggle with this.
 * Day3: Subtraction across zeroes**




 * Day4: Subtraction word problems**


 * Day5: Review and Assess!!!**