筛选
shāi xuǎn · HSK 7
to filter
筛 sieve + 选 choose: sift then pick out = to filter
筛 (shāi) is a sieve and 选 (xuǎn) means to choose, so 筛选 is the two-step act of sieving material and then selecting what passes through.
筛 — bamboo radical 竹 + 师 (shī, phonetic)
筛 is a phono-semantic compound. The bamboo radical 竹 on top signals the meaning, since traditional sieves were woven from thin bamboo strips. The lower component 师 (shī) supplies the sound, giving the modern reading shāi. The character means 'sieve' or 'to sift'.
选 — 辶 walk + 巽 (xùn, phonetic)
选 combines the walking radical 辶 with 巽, which suggests the sound. The original sense relates to going through or passing by, extended to 'picking out' or 'choosing' from a group. The simplified form replaces the older 選.