This lab benefits from access to the outdoors (more than just a playing field, although there may be more diversity there than you think). Students will need to search in flower beds, fields of wildflowers or weeds, and some variety of trees. This lab is well suited to the beginning of the school year as the growing season winds down, however there are seeds to be found throughout the year, and if it is winter, you should be able to complete this lab with seeds collected at the market as well.
The basic plan is for students to collect and observe a variety of seeds. Consider supplementing the small seeds of weeds and wildflowers with some unusual seeds like lima beans, chick peas, citrus seeds, squash seeds, and coconuts. After making observations of the variety of seeds, students are asked to come up with many questions about seeds. I allow students to use what their classmates share to supplement their own questions.
One key point I like to stress is that seeds are not only for reproduction. Seeds allow plants to survive inhospitable conditions like cold or drought. In addition to these purposes, ask students to consider what else seeds do. Ask if plants are able to move from one place to another. Take a moment to discuss how seeds allow plants to move.
After looking at the seeds and recording observations, students each choose one question to investigate. If you have online access, many of their questions can be pursued that way. I am a big proponent of encyclopedias. They are dense with information, each entry has an identified author, and they are readily available. General science texts are also a good resource for basic information.
The accompanying rubric does not require students to find the answer to their selected question. They do need to try, and it may be useful to have them record some information they find even if it does not relate directly to their chosen question. I find that my students consider the internet to be a reliable source of information, and it is often their go-to source. I like to point out to them after this activity that for some of them it was not, and for others the encyclopedia was more fruitful.
In addition to the activity page in Word and PDF, I have included some photos of the results from our latest seed hunt.