"MATEMĀTIKA 3. KLASEI"
Garumu vai attālumu var mērīt milimetros, centimetros, decimetros, metros, kilometros.

Svarīgi ir zināt sakarības starp šiem mēriem.
$\begin{array}{l}1\phantom{\rule{0.147em}{0ex}}\mathit{cm}\phantom{\rule{0.147em}{0ex}}=\phantom{\rule{0.147em}{0ex}}10\phantom{\rule{0.147em}{0ex}}\mathit{mm}\\ 1\phantom{\rule{0.147em}{0ex}}\mathit{dm}\phantom{\rule{0.147em}{0ex}}=\phantom{\rule{0.147em}{0ex}}10\phantom{\rule{0.147em}{0ex}}\mathit{cm}\phantom{\rule{0.147em}{0ex}}=\phantom{\rule{0.147em}{0ex}}100\phantom{\rule{0.147em}{0ex}}\mathit{mm}\phantom{\rule{0.147em}{0ex}}\\ 1\phantom{\rule{0.147em}{0ex}}m\phantom{\rule{0.147em}{0ex}}=\phantom{\rule{0.147em}{0ex}}10\phantom{\rule{0.147em}{0ex}}\mathit{dm}\phantom{\rule{0.147em}{0ex}}=\phantom{\rule{0.147em}{0ex}}100\phantom{\rule{0.147em}{0ex}}\mathit{cm}\phantom{\rule{0.147em}{0ex}}=\phantom{\rule{0.147em}{0ex}}1000\phantom{\rule{0.147em}{0ex}}\mathit{mm}\\ 1\phantom{\rule{0.147em}{0ex}}\mathit{km}\phantom{\rule{0.147em}{0ex}}=\phantom{\rule{0.147em}{0ex}}1000\phantom{\rule{0.147em}{0ex}}m\end{array}$

Sakarības ir jāzina, lai varētu mērus saskaitīt un atņemt.
Piemērs:
Saskaiti $32\phantom{\rule{0.147em}{0ex}}\mathit{dm}\phantom{\rule{0.147em}{0ex}}+\phantom{\rule{0.147em}{0ex}}12\phantom{\rule{0.147em}{0ex}}\mathit{cm}$!
Nedrīkst vienkārši saskaitīt $$32$$ ar $$12$$, jo kāda tad būtu gala iznākuma mērvienība?
Sakarības ir nepieciešams izmantot, lai garumus salīdzinātu.
Piemērs:
Salīdzini $4\phantom{\rule{0.147em}{0ex}}m\phantom{\rule{0.147em}{0ex}}20\phantom{\rule{0.147em}{0ex}}\mathit{cm}$ un $32\phantom{\rule{0.147em}{0ex}}\mathit{dm}$!
$4\phantom{\rule{0.147em}{0ex}}m\phantom{\rule{0.147em}{0ex}}20\phantom{\rule{0.147em}{0ex}}\mathit{cm}=40\phantom{\rule{0.147em}{0ex}}\mathit{dm}+2\phantom{\rule{0.147em}{0ex}}\mathit{dm}=42\phantom{\rule{0.147em}{0ex}}\mathit{dm}$
$42\phantom{\rule{0.147em}{0ex}}\mathit{dm}\phantom{\rule{0.147em}{0ex}}>\phantom{\rule{0.147em}{0ex}}32\phantom{\rule{0.147em}{0ex}}\mathit{dm}$
Tātad $4\phantom{\rule{0.147em}{0ex}}m\phantom{\rule{0.147em}{0ex}}20\phantom{\rule{0.147em}{0ex}}\mathit{cm}>32\phantom{\rule{0.147em}{0ex}}\mathit{dm}$

Var pāriet arī uz centimetriem:
$\begin{array}{l}4\phantom{\rule{0.147em}{0ex}}m\phantom{\rule{0.147em}{0ex}}20\phantom{\rule{0.147em}{0ex}}\mathit{cm}=400\phantom{\rule{0.147em}{0ex}}\mathit{cm}+20\phantom{\rule{0.147em}{0ex}}\mathit{cm}=420\phantom{\rule{0.147em}{0ex}}\mathit{cm}\\ 32\phantom{\rule{0.147em}{0ex}}\mathit{dm}=320\phantom{\rule{0.147em}{0ex}}\mathit{cm}\\ 420\phantom{\rule{0.147em}{0ex}}\mathit{cm}>320\phantom{\rule{0.147em}{0ex}}\mathit{cm}\end{array}$
Kurmītis no savas mājas līdz pļavai nobrauca $$1$$ kilometru.
Vai tas ir daudz vai maz?
$1\phantom{\rule{0.147em}{0ex}}\mathit{km}=1000\phantom{\rule{0.147em}{0ex}}m$

Pieauguša cilvēka solis ir aptuveni $$1$$ metrs.
Pamēģini saskaitīt $$1000$$ savus soļus, lai redzētu, cik apmēram ir $$1$$ kilometrs.