This study was conducted to analyse the practice of Biology teachers in formative assessment of Biology content and English language as a language supportive pedagogy in the Biology subject. The target population was 33 ordinary level secondary schools under the PITA project in Meru district council. Of the total schools, five were sampled for this study. The respondents included 70 students and 5 Biology teachers making 76 total participants. The convergent parallel research design under mixed method research approach was used. Purposive and stratified-random sampling techniques were used to select teachers and students respectively. The researchers collected data using questionnaires, interview, observation, and document analysis guides. The results showed that the Biology teachers use mainly question & answer, group assessment and short tests in Biology subject assessment. The formative assessment in Biology also involves the assessment of language aspects such as checking spelling, pronunciation, grammar and tenses. The results also revealed three main challenges: difficult biological terms, language of instruction and time in formative assessment of both Biology content and language. The researchers recommended the use of more techniques, Biology dictionary and enhancement of cooperation between Biology and language experts in formative assessment of Biology content and English language.

Keywords: Keywords: Biology, formative assessment, content, language, PITA, secondary schools