Encourage me to sing or hum motifs from songs that I like

I’m likely to pick up first on the line that is repeated most often in a song

Encourage me to sing the fragments of a melody that I’ve heard a lot, by using a microphone and amplifier
Use ideas from Soundabout Music Tracks: Motifs
To start with, bits of tunes may only approximate to the originals, and I may mix up parts of melodies from different songs, but that’s all part of the learning process and is a sign of my musical creativity in action!
Change the volume (and, if possible, the bass and treble components) coming through the speaker, so I hear my voice sounding different
If the equipment has the facility, try introducing different effects such as echo and reverberation
You could use a looping app to build my short bursts of melody into longer sequences
Record my efforts so I can hear them later