Today we really dived into using number lines as a strategy for solving subtraction.
There are two ways to do it.
We can start at the big number and then make jumps back until we've jumped the whole number.
We can start at the little number and make jumps until we get to the big number.
I personally like the second method because I think it is easier to add than subtract.
Our place value and data units are over.
We'll definitely still be reviewing those in class and having homework about those things but we're moving on to bigger and better things now.
Word problems!
Addition and Subtraction problems!!!
This is one of my favorite things to teach in math because the kiddos can get so creative in the way that they solve math problems.
I'm always surprised when I see the way students model their thinking.
The TEK we are working on is:
3.4A I will solve one-step and two-step problems involving addition and subtraction within 1,000.
3.5A I will represent one- and two-step problems involving addition and subtraction of whole numbers to 1,000 using pictures, number lines, and equations.
3.7C I will determine the solutions to problems involving addition and subtraction of time intervals in minutes.
Now that we've finished place value, it is time to move on to ADDITION and SUBTRACTION!!
This is the main TEK we are focusing on:
3.4A solve with fluency one-step and two-step problems involving addition and subtraction within 1,000 using strategies based on place value, properties of operations, and the relationship between addition and subtraction
The main strategies we focus on are the number line, bar model, standard algorithm, expanded form and picture.
I like for students to use rounding to check if their answer is reasonable.
For example, if I'm adding 253 and 423 I know my answer will be about 700 because 253 rounds to 300 and 423 rounds to 400. 300+400 =700
Here are some good games for practicing addition/subtraction skills.
This math game is a way of practicing place value and subtraction. Students have a board full of numbers. They also have a stack of numbers.
Students roll the dice to find out how many tens they are subtracting. They subtract that amount from the first card in their stack. Then when they get the answer, the place a cube on that number on their board.
The goal is to get 5 in a row.. like Bingo.
Today to practice our subtraction skills we played a pretty fun game.
It is played in pairs. Each kiddo starts at with 200 points. The first person to get below 0 wins. One person is the "odd" team, the other is the "even" team.
You roll a dice two times to get a double digit number. If the number is an even number, the "even" team subtracts it. If the number is an odd number, the "odd" team subtracts it.
The best part of creating things on teachers pay teachers is watching my own students use it!
I think math can sometimes can monotonous, however... I really want them to practice their double digit subtraction skills.
I've been noticing that some of my kids are so excited about regrouping, that they do it even when they don't have to!
So I created a sorting activity for them to do!
They had to sort into "more on the floor, go next door, get ten more" or "numbers the same, zero's the game" or "more on top, no need to stop"
When I was in school, I learned the old school, "borrowing" way. I did it, and I got my answers correct, but I had no idea why I was crossing out the tens and changing the ones. It was totally mindless for me.
While it was nice that I got my answers right, it is more important to deeply understand place value.
That is part of the reason we teach all sorts of methods before we go into "borrowing."
Also, it is no longer called "borrowing." It is now called, REGROUPING.
The way we are told to teach regrouping is by first looking at expanded form.
Expanded form means that you look at the value of every digit in a number and adding them together.
For example 623 becomes 600 + 20 + 3
So how does that translate to borrowing regrouping?
If I am taking 623- 351 that becomes
600 + 20 + 3 I can take 1 away from 2. But I cannot take 50 away from 20. I need to borrow
-300 + 50 +1 regroup. So I change the problem into
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