Ends 8.15.

Ocean Odyssey
Is Kai at risk of being found? (R) (S)
Continues on Friday at 7am

7.25 Histeria
China is on the map as Father Time, Big Fat Baby and Loud Kid Kiddington continue their animated guide. (R) (S)

7 45 Get Your Own Back
Grown-ups risk gunging by vengeful children. Shown yesterday at 4.10pm on BBC1 (S) (W)

Ends 10.50.

Bob the Builder
Skateboarding into town, Spud runs into Bob's traffic-control system.
BBC BOB THE BUILDER MAGAZINE: £1.40. CD-Rom, for PC and Playstation, price £19.99; Bob the Builder - Fix It Fun!, on Game Boy Colour, £24.99

8.25 The Story Makers
The trio today try to find out what words rhyme with Jelly?

8.40 Clifford the Big Red Dog
How did Emily and Clifford first get together? A story told in flashback reveals everything.

9.00 Teletubbies
In this double bill, the pals play a game that involves looking for one another, then they join up and dance.

9.50 Playdays
Peggy has her work cut out making sure Daisy is ready for the big show.

10.10 Tweenies
Double bill. Max helps the friends to make a summer collage, then Judy takes a trip to a dinosaur park.

Repeats are not indicated.
10 50 Come Outside (ages 4-5) Water 1868826 11.05
Numbertime (ages 6-7) Addition and Subtraction: Subtracting One from Another 9289623 11.20 Words and Pictures Plus (ages 6-7) Long Vowel Spelling
11.35 Cats' Eyes (ages 5-7)
The Environment: Habitats and Humans 9906517 11.50
Hands Up! (ages 5-7) Goodnight Owl 6735791 12.05 Pod's Mission (ages 7-9) Teeth and Eating 4164826 12.20 Maths Challenge (ages 9-10) TV Workout Year (part 6)

Animations, songs and sketches show the relationship between practical problem solving and written calculations using addition and subtraction.

Business roundup, with Adrian Chiles and Adam Shaw.

Quarter-final coverage from the Crucible. The difference between progression and elimination here is f 38,000. With Hazel Irvine, Steve Davis and John Parrott. Plus the 2.00 and 2.30 races from Ascot on the course's opening day of the flat-racing season. (S-not racing)

Events at Westminster, including Prime Minister's Questions. Presented by Nick Robinson.

(Contact details on Tuesday)

(Digital: BBC London News)
Weather

Clare Balding hosts coverage of the 4.10 race from Ascot. Plus further quarter-final action from Sheffield. In an all-English clash at this stage last year, Ronnie O'Sullivan beat
Peter Ebdon 13-6 to book his place in the last four. (S - not racing) WEBSITE: www.bbc.co.uk/snooker

Raging Abe Simpson and his Grumbling Grandson in "The
Curse of the Flying Hellfish ". Grampa Simpson battles Mr Burns for a priceless art collection that they seized back during the Second World War.

Roxy Music frontman Bryan Ferry delivers a taster from his new album, Frantic, and there are classic cuts from the archives by Aztec Camera, Hazel O'Connor , Echo and the Bunnymen, pop ragga duo Louchie Lou and Michie One, and the Jacksons. Plus Tammy Wynette teaming up with pop pranksters the KLF for their 1991 number-two hit Justified and Ancient. Narrated by Steve Wright.
Producer Mark Hagen WEBSITE: www.bbc.co.uk/totp Top of the Pops is on Friday at 7.30pm on BBC1
BBC TOP OF THE POPS MAGAZINE: £1.90. New issue now on sale 1 May

As this year's world-championship quarter-finals enter their respective concluding sessions, Hazel Irvine presents further live coverage from the Crucible. Matches are played over the best of 25 frames.

In an edition of the domestic makeover show that was first shown last year, presenters Laurence Llewelyn-Bowen and Diarmuid Gavin visit the Kent town of Bromley to imbue a home and garden with an exotic Mexican flavour. The tiny kitchen and dark dining room are knocked together and Llewelyn-Bowen comes up with a pink-and-white colour scheme. Meanwhile, in the garden, Gavin constructs a i series of arched steps, a courtyard seating area and an "infinity" water feature - all in the same vivid pink.
Director Micci Billinger ; Series producer Amanda de Ryk tS) WEBSITE: www.bbc.co.uk/homefront
BBC GOOD HOMES MAGAZINE: monthly, price L2.30. New issue on sale 3 May

Who will figure in the tournament's final four as the quarter-finals reach their climax? Two former champions exited at the last-eight stage in 2001 as Stephen Hendry and Ken Doherty were eliminated, respectively, by Matthew Stevens and John Higgins. RayStubbs,
Steve Davis and John Parrott introduce the action from Sheffield. Producer Alison Witkover ; Executive producer Graham Fry WEBSITE: www.bbc.co.uk/snooker

Analysis of the national and international news. Presented by Jeremy Paxman.

Highlights of today's quarter-final action in Sheffield, plus a look ahead to tomorrow's best-of-33-frame semi-finals.
Commentary by Clive Everton , Ray Edmonds ,
Dennis Taylor , Willie Thorne and John Virgo.

Analysis of the day's major political events, plus a preview of the morning papers. Presented by Andrew Neil.

Repeats are not indicated.

Open University

12.30 Driving While Black
exploring racial tensions in the US state of Cincinnati.

1.00 Women and Allegory: Gender and Sculpture in Two Societies
what can be learned by comparing allegorical images of women from eastern and western cultures?

1.30 The Black Triangle
reporting on attempts to clean up the environmental legacy of communism in the most polluted area of Europe. (S)

Secondary Schools
2.00 Mathsphere Edits: Shape. Space and Measures
a blend of short clips and real-life examples to spark students' interest and prompt further investigation.

Languages
4.00 Espana Viva (parts 7-8)/Spanish Globo (parts 9-10)
language course, plus a Spanish animation.

Working in Engineering
5.00 Ancient and Modern
Fred Dibnah celebrates great achievements in civil engineering.

Open University
6.00 Kedleston Hall
a look at Robert Adam's architectural masterpiece.

6.30 Picasso's Collages 1912-13
explanations of two of the artist's controversial pieces, completed on the eve of the First World War.