Amen to that stupid poem. I'm a USA born white girl, and that poem broke me. I tried to read it aloud and got part way through before my tongue / brain made me give up. It's evil.
Can you say squirrel? My trick with this word is to use different words. Start with the word "whirl". Repeat this word a couple of times to get your mouth around it. Then say the "sch" from the word "school". "Sch"... + ..."Whirl", "Sch".. + .."Whirl", "Sch". + ."Whirl", "Sch" + "Whirl", "Sch" "Whirl", "Sch-Whirl", ""SchWhirl". Looks horrible typed but it works on the tongue. Just need to get that sound glide exiting "sch" into "whirl". If you end the "sch" with your lips pursed in anticipation for the "oo" sounds in school, it sets you up for the "wh".