Two curious first-graders decide to steal a turtle named Rocket from a living corner to conduct a risky experiment — they want to put it under the tank in order to check the carrying capacity and strength of the shell. But their classmate Tanya is smarter than her friends: with the help of adults, she manages to organize the rescue of the unfortunate turtle.
| Actor | Role |
|---|---|
| GGalina BudanovaTanya Samokhina | Tanya Samokhina |
 Alexey ErshovVova Vasilyev | Vova Vasilyev |
| AAndrei SamotolkinVova Didenko | Vova Didenko |
| MMikhail MartirosyanVova Manukyan | Vova Manukyan |
 Yelena RyabukhinaElla | Ella |
| GGalina VerbitskayaBella | Bella |
| AAleksei GolubevGolubev | Golubev |
| IInga VolodinaInga | Inga |
| MMaryana SmirnovaKatya | Katya |
 Aleksey BatalovSamokhin | Samokhin |
 Iren AzerAnna Sergeyevna | Anna Sergeyevna |
 Liliyan Malkinagym teacher | gym teacher |
 Zoya FyodorovaViktoriya Mikhailovna | Viktoriya Mikhailovna |
 Rina Zelyonayascientific secretary at the museum | scientific secretary at the museum |
 Vera Burlakovaschool janitor | school janitor |
 Valentina Berezutskayajanitor | janitor |
 Rolan BykovDidenko's grandfather / Manukyan's grandmother (uncredited) | Didenko's grandfather / Manukyan's grandmother (uncredited) |
 Emiliya Miltonпожилая актриса | пожилая актриса |