1. 涂一涂，算一算。

$ \frac{1}{4} + \frac{3}{8} = \frac{(\ \ \ \ \ )}{(\ \ \ \ \ )} + \frac{(\ \ \ \ \ )}{(\ \ \ \ \ )} = \frac{(\ \ \ \ \ )}{(\ \ \ \ \ )} $

$ \frac{1}{5} - \frac{1}{10} = \frac{(\ \ \ \ \ )}{(\ \ \ \ \ )} - \frac{(\ \ \ \ \ )}{(\ \ \ \ \ )} = \frac{(\ \ \ \ \ )}{(\ \ \ \ \ )} $

$ \frac{1}{4} + \frac{3}{8} = \frac{(2)}{(8)} + \frac{(3)}{(8)} = \frac{(5)}{(8)} $
$ \frac{1}{5} - \frac{1}{10} = \frac{(2)}{(10)} - \frac{(1)}{(10)} = \frac{(1)}{(10)} $

2. 直接写得数。
$ \frac{1}{4} + \frac{1}{8} = $$ $$ \frac{5}{9} - \frac{7}{18} = $$ $$ \frac{1}{3} - \frac{1}{12} = $

$\frac{1}{4} + \frac{1}{8} = \frac{2}{8} + \frac{1}{8} = \frac{3}{8}$
$\frac{5}{9} - \frac{7}{18} = \frac{10}{18} - \frac{7}{18} = \frac{3}{18} = \frac{1}{6}$
$\frac{1}{3} - \frac{1}{12} = \frac{4}{12} - \frac{1}{12} = \frac{3}{12} = \frac{1}{4}$

3. 列式计算。
(1)
$\frac{9}{16}$m比$\frac{1}{4}$m多多少米？
(2)
$\frac{19}{24}$时与$\frac{3}{8}$时相差多少时？

(1)
$\frac{9}{16}-\frac{1}{4}$
$=\frac{9}{16}-\frac{4}{16}$
$=\frac{5}{16}(m)$
(2)
$\frac{19}{24}-\frac{3}{8}$
$=\frac{19}{24}-\frac{9}{24}$
$=\frac{10}{24}$
$=\frac{5}{12}(时)$