Words with more than one syllable in English have a syllable that pronounced with additional emphasis.
Example
‘Photograph' has word stress Ooo (stress on the first syllable), ‘photographer' has word stress oOoo (stress on the second syllable).
In the classroom
There are many ways to indicate word stress visually, including the method above, putting a line above main stress and below secondary stress, and using a board marker to partially rub out unstressed syllables.
Further links:
https://www.teachingenglish.org.uk/article/word-stress
https://www.teachingenglish.org.uk/article/integrating-pronunciation-classroom-activities
https://www.teachingenglish.org.uk/article/dictation-1-correction-techniques
https://www.teachingenglish.org.uk/article/global-english-teaching-pronunciation
https://www.teachingenglish.org.uk/article/teaching-speaking-unit-4-stress-intonation