I will make a lesson plan for next week.
シラバス is a loanword from English 'syllabus' and often refers to a course outline or syllabus in a university context. 授業計画 is a native Japanese compound that can refer to both a syllabus and a more detailed lesson plan, and is used in a wider range of educational settings.
Compound of 授業 (class, lesson) and 計画 (plan). The exact historical derivation is uncertain, but the word follows standard Sino-Japanese compounding patterns.