Here's an imaginative but simple & cheap kids project that fosters both creativity AND solar insights-ideal for 8-10 year olds! It's based around a ~$2 tube style solar garden lamp and blown out egg shell.
Step 1: Solar Easter Egg lamp
The basic of the Instructable involves decorating a carefully emptied egg shell, then placing it over an up-ended solar garden lamp base. The effect in the dark is MAGICAL, & a suprising ammount of light is produced. It's ideal for kids bedside lamps, as parts & electrics are completely safe. The lamp's internal NiMH (Nickel Metal Hydrid) battery will run for several hours, and readily recharges when the solar cell is exposed to the sun.
Step 2: Solar garden lamps
Solar garden lamps abound in the US$2 range, but specials at times slash the price. Pre Easter 2013 New Zealand's "The Warehouse" chain were selling 4 for NZ$5 = ~ US$1 each. Yikes -the parts alone within are worth more than this, especially the rechargeable AAA NiMH battery.
The lamps come with well written instructions, and (if time allows) these should be carefully read through before starting the project.
Step 3: Safety alert!
Alert: Most boys WILL promptly play "warriors" if issued the tubes & pointed ground probes! The ends are VERY sharp, so either trim them back or remove them from the issued materials entirely, otherwise accidents may occur...
To further stress this point check some "Room 3" kids at a rural New Zealand school who've just been issued the lamps. You can see at a glance that a LOT of stage mike/Olympic torches/decoration etc hi jinks may promptly result!
Step 5: Rain gauge?
The clear lamp surround is just on 50mm (2") tall internally, & if supported on 2 tubes it'll make a handy rain gauge! ( A single tube may do but rain splashes from the nearby ground can bias readings). Note- a small drainage hole in the lamp surround will first need blocking with hot melt glue.