If you ask Tiemo Dionne what caused the gooey and grotesque wounds on his left temple and forearm, he'll give you a plethora of answers.

"Car accident. Pit bull. Train accident," the 7-year-old Lambertville boy said while holding his arm up to show off the giant gashes. "Just kidding."

Instead the gooey mess was part Vaseline, part red dye, part gauze, and part cocoa - to add a dark, muddy look - and didn't hurt at all. The fake blood and flesh wound was one of the hands-on experiments offered at COSI Toledo as part of the center's Spooky Science event.

Spooky Science will return to COSI again this weekend and includes demonstrations by COSI staff members that show everything from smoking cauldrons to scary noises made with household items.

"They are all things you can do at home," said Carl Nelson, exhibit and facilities director. "These you can do for Halloween."

Besides the table of ingredients for fake blood and flesh manned by teen volunteers, COSI patrons could get a take-home sample of slime - made to the color of their choice - or decorate a mask with beads, feathers, and glitter.

While the "monster slime" and mask-making is a part of COSI's traditional Halloween setup, the science demonstrations are new this year. Three times a day throughout the weekend, the lights are lowered and a set of bleachers on the center's main floor fills up with those ready to watch safe science experiments they can reproduce at home.

Jennifer Kettler and her daughter, Mallorie Henderson, were at COSI yesterday, enjoying science with members of Mallorie's Brownie troop. Together they watched as COSI staff rubbed a strip of cloth soaked in soapy water over a cauldron filled with dry ice to create a large ghostly bubble that eventually popped.

Also during the show, staff created "ghost voices" by shaking a balloon with a hex nut inside it and by pulling on a wet string attached to the bottom of a plastic cup.

But it was during the finale, when staff used a chemical reaction to "self-carve" a pumpkin, that the majority of visitors reacted to the experiments.

"It was pretty neat," said Mallorie, 9, of Toledo. "I like the exploding pumpkin."

Mr. Nelson explained that the pumpkin already was carved but had the pieces put back in place. Then, by using fire to light a chemical mixture - something he warned should not be done at home - staff members were able to create a reaction that blew the pieces of pumpkin out.

"If you do it wrong, it's the exploding pumpkin," he explained. "If you do it right, it's the self-carving pumpkin."

Erika Reyes of Toledo brought her two children, Miranda Stricklen, 12, and Isaiah Reyes, 7, to COSI as part of a regular monthly trip to the science center. The three stood in front of the mask-making table, where Miranda and Isaiah glued feathers and glitter to white, plastic masks.

Because they are COSI members, the family spends a lot of time at the science center, Ms. Reyes said. And events like Spooky Science make every trip fun, she added.

"They always have something different," she said.

Contact Erica Blake at: eblake@theblade.com or 419-724-6076.

First Published October 23, 2006, 12:13 p.m.