All right, this is fifth-grade module five less than eighteen and in this lesson we're continuing to classify Two-dimensional figures specifically quadrilaterals today, we're going to be focusing on
Rectangles and rhombuses to talk about the differences between those things and what they are and basically
what um let's see, what a
Rhombus is it's a quadrilateral
Where all four sides have the same length now, that sounds like it's a square, right?
Quadrilateral where all four sides at the same length?
Ah, but a square has 90-degree angles where a rhombus does not necessarily need to have
All four angles being are having the angles being ninety degrees
It's just the only requirement for a rhombus is that it's a quadrilateral where all four sides are the same length
Rectangle more familiar for most of our fifth graders, which is it's a quadrilateral?
With four right angles, that's the definition of a rectangle now
Oftentimes we say two of the lines are parallel the other two are parallel these two are equal and these two are equal
But that's extra information that we don't have to include
And so a rectangle is a quadrilateral with four right angles
Rhombus is a quadrilateral where all four sides are the same length, so let's get started on this
So we're being asked to draw a rhombus with no right angles now remember what a rhombus is it's got to have four
equal sides and
So let's get a slightly thicker pen and a rhombus where it's got four equal
sides so I'm gonna draw this that way and
In order to make it add the equal length, it's got to go that way and then here and then
Here now is that the only possible rhombus that we can create. No. There's others that we could have done, but
That's the one I'm gonna draw and I know it's a rhombus because all four sides are the same length
And I happen to win
Because there are no right angles now
Question B. Says now draw a rhombus where you do have four right angles and of course. This is going to look like
now it's not easy because
The lines we had kind of have to go against the lines
But what I'm trying to draw because the square now how do I know it's a rhombus well?
It's a rhombus because it has four sides that are all
Equal to each other now, I also happen to draw it so that it had four right angles
Because that's what it asked for
So next one down here a rectangle with not all sides being equal
So what would a rectangle look like if not all of the sides are?
Equal well, here's a rectangle now. What was the rule for how do I know it's a rectangle well?
I know it's a rectangle because it has
four
90-degree angles
That's the only requirement for it to be a rectangle
But I did the added benefit of saying that and showing
You know drawing a picture where they're not all
the same side
side lengths in fact this left side is equal to this right side and
the top base is equal to the bottom base and
and that
Satisfies this where they're not all sides are equal
Now here, it says draw a rectangle where all sides are equal
So I know that all sides have to have I mean all angles have to be 90 degrees because that's a rectangle
But now I have to draw all four sides being the same well. What is that going to be?
something with all 90-degree angles
That makes it a rectangle
And the fact that all sides are equal boom boom boom and boom makes it a square means. It's a square
Now here it says a rhombus has a perimeter of 217 centimeters
what is the length of each side of the rhombus so the idea is well let's start with a rhombus and
We know that the perimeter
is
217 so that means if we were to add this side
Plus this side Plus this side Plus this side we would get
217 now the rule for it being a rhombus is that all four sides are
equal so
If we know the perimeter is 217
We could divide by 4
to figure out the length of each one of those sides
and
I get
remainder of 1 so that's going to be 54 and
1/4 so each side is 51 and 1/4
centimeter
And
The last slide I'm going to do something a little bit different
It says list all the properties that are rhombuses that rhombuses share right well. I want you to go to this website
Tube dot geogebra dot org
m
5 8 6 3 5 so you got to do everything correctly and
I know it works. Cuz I just chucked it
And I just want you to play with this applet basically it allows you to
dynamically play with a rhombus and look at all of the characteristics of a rhombus and the properties and just
play
Same thing down here with rectangles. It's a different URL
tube geogebra org m 5 4 8 1 0
And just play basically parents and teachers what we're going to be looking for is for rhombus. We're looking for four equal sides
or
equal sides
We're going to be looking for students to talk about the diagonals that they're equal
They're not equal diagonals that
the diagonals
Don't have to be equal
But the diagonals are
Bisected remember what that means that means each?
Diagonal is cut in half by the other diagonal right cut into two pieces
Equal pieces and there's other other things we could put in that list
We're gonna have opposite angles being equal. We're going to talk about
Consecutive angles are gonna. Have a sum of 180. There's a bunch of things that students might say
Same thing down here
There's a lot of different properties, but we're specifically going to be looking for 90-degree angles
for 90 degree angles we're gonna be looking at
parallel
Sides we're gonna want want to hear that opposites are parallel so
That opposites are parallel. There's a variety of other
properties that students might say so we just want them to play with these two URLs and
Come up with their list and it's perfectly fine. If their list is incomplete
What's more important is to allow students to play with the?
geogebra the dynamic geometry software
and
that wraps up fifth grade module five lesson 18 focusing on rectangles and
rhombuses