salmabalga 1 verbete sample size 1 verbete sampling 1 verbete sampling frequency 1 verbete sanitation 1 verbete scaffolding 2 verbetes scalp 1 verbete SVET (Scanning Vibrating Electrode Technique) 1 verbete scope 1 verbete screening 1 verbete second language 1 verbete second language learning 1 verbete secondary qualities 1 verbete self-assessment 1 verbete self-attention mechanism 1 verbete self-belief 1 verbete self-directed language learning 1 verbete self-efficacy 1 verbete self-fulfillment 1 verbete self-paced learning 1 verbete