These are my go-to websites:
"An Exploratorium Snack is a hands-on science activity. Science Snacks are tabletop exhibits or explorations of natural phenomena that teachers or students can make using common, inexpensive, readily available materials.
Science Snacks are divided into easy-to-follow sections that include instructions, advice, and helpful hints. Each one begins with a photo and/or video, a short introduction, and a list of materials. Other sections include assembly instructions, how to use the activity, and explain what’s going on, science-wise. Most Science Snacks can be built by one person; we indicate if a partner or adult help is needed, this is indicated. A section called "Going Further" offers interesting bits of additional scientific and historic information."
http://www.science-sparks.com/Very nice website and blog with lots and lots of activities for younger pre-school to lower elementary school children. More for one-on-one activities, but many can be scaled to small groups.
"Here at Science Sparks we are passionate about making science fun for kids. All our activities are easy to do and use only equipment and materials commonly found around the home. Science for kids doesn’t have to be complicated and boring, it can be great fun for both children and adults.
Science based activities offer endless creative learning opportunities and are a great way to spend time with your children. We’ve had some of our best chats while drawing on filter paper and making patterns in milk.
Science activities can also be fantastic for inspiring reluctant readers or children who like to be very hands on with their learning. Children are naturally curious and science activities are a great way to help them explore the world around them. Learning how to think logically and follow a scientific process has huge benefits to children as they grow up, helping them to plan, communicate, work creatively, solve problems and much more."
"The TeachEngineering digital library is a collaborative project between faculty, students and teachers associated with five founding partner universities, with National Science Foundation funding. The collection continues to grow and evolve with new additions submitted from more than 50 additional contributor organizations, a cadre of volunteer teacher and engineer reviewers, and feedback from teachers who use the curricula in their classrooms.
TeachEngineering is a searchable, web-based digital library collection populated with standards-based engineering curricula for use by K-12 teachers and engineering faculty to make applied science and math come alive through engineering design in K-12 settings. The TeachEngineering collection provides educators with *free* access to a growing curricular resource of activities, lessons, units and living labs."
- One-off activities are completed in one session. They are often highly engaging and can have a real wow factor.
- Short projects are any activity that takes club members two to three sessions to complete. Many of the shorter projects will include demonstrations or experiments that can be used as one-off activities.
- Long projects are activities that take half a term or more to complete and might be considered a long project. Completing a long project can be very rewarding, especially if there is an award or a prize involved.
Each activity is categorized as Science, Technology and Engineering, Maths, or Cross Curricular.