ERIC provides access to journal articles, as well as ERIC documents. You can use ERIC to search for articles on any topic, many of which will be in the journals listed on this page. Use the journal links to browse only within that journal.
For lesson plans use terms like: Class Activities, Lesson Plans, Instruction, etc.
Also include terms for your subject: frogs, climate change, etc.
And age group: elementary, Grade 4, etc.