hey it's Kalei and this lesson we're going to learn to measure to the half
and quarter inch let's go in our lessons so far we've been measuring the lengths
and Heights of objects to the whole inch let's take a look at this redline how
long is it we can see that it lines up with seven inches in fact it lines up
perfectly with seven inches this means that the line is seven whole inches but
what if it wasn't lined up perfectly with seven inches what if instead our
redline ended somewhere between seven inches and eight inches in this lesson
we're going to learn how to measure things that are between whole inches
let's start with inches I've zoomed way in and our ruler here so we only see the
first three inches let's talk about what an inch is this blue rectangle is one
whole inch in the United States an inch is the smallest unit of measurement for
length and height but we know that there could be a rectangle that is smaller
than one whole age like this red rectangle if we want to measure
something that is smaller than an inch we have to divide the inch into parts
let's use our blue rectangle to help us see remember we measured our blue
rectangle to be exactly one whole inch now if we draw a line right down the
middle of our rectangle what do we get well now we have two rectangles that are
each half an inch so we see that we can divide an inch into two parts that each
equal half an inch now what if we draw a line right down the middle of both of
the half rectangles now we have four rectangles now using
what we know about fractions if we take one thing and divide it into four parts
each part is one-fourth this shows us that we can divide one whole inch into
four parts and each part will be 1/4 or 1/4 of an inch
now let's take a look at the ruler again do you notice anything about the marks
on the ruler yeah these big lines here represent a whole inch and then we see
these three smaller lines in between what do you think that this longer line
in the middle represents well if we compare the distance from the taller
middle line to the whole inch lines it appears to be right in the middle so
this is the half inch mark and these shorter lines are cutting halfway
between the half inch mark so they must be the quarter inch marks let's zoom in
now between the one and two inch marks and do a quick fraction review remember
each of these distances is 1/4 so if we're going to count them we would have
1/4 2/4 3/4 before we would come to the next whole number and we can simplify
2/4 to what yeah that's right 1/2 now that we know how to divide an inch in
two parts let's measure the length of this Green Line so if it starts here at
the edge of the inch mark and it goes a quarter a half three quarters across the
inch this Green Line is three quarters of an inch let's do a few examples now
without our extra markings what is the length of this rectangle it starts at
zero and it goes past the three whole inch mark but by how much well let's
count we have three and a quarter three and two quarters and three and two
quarters is the same as three and so this rectangle is three and a half
inches long how about this one it's longer than the four whole inch mark and
goes to the first marker which we know is a quarter so this rectangle is four
and a quarter inches long now let's take a quick look at our original ruler and
find the half inch and quarter inch marks we can zoom in to make it easier
to see now notice between the one inch and the two inch marks we have all these
little lines let's count how many longer lines there are just one two three four
five six seven and one would make eight so the halfway point would be at line
four if this is the halfway point between one inch and two inches we know
that this is the half inch mark and if we cut our half-inch in half we find the
quarter inches here and here now using our ruler let's measure this yellow
rectangle I see that it lands between one inch and 2 inch and here's my
quarter inch mark and my half inch mark and my three quarter inch mark and the
line ends right here so this rectangle is 1 and 3/4 inches long now you know
how to divide an inch into parts practice what you've learned by doing
the online games and quizzes have fun and remember to always be clever