In December 2001, NBC reached a partnership with Discovery Communications, in which its cable channel Discovery Kids would produce a new three-hour Saturday morning block for the network that would feature programming that met the educational programming guidelines enforced by the Children's Television Act. The block would replace TNBC, a block of live-action series aimed at a teenage audience whose creation was motivated by the success of its series Saved by the Bell. By 2001, TNBC had been suffering from declining viewership; according to Nielsen Media Research, the block was registering a median viewer age of 41. Discovery Kids on NBC debuted on October 5, 2002, with its initial lineup incorporating three new original series and one existing Discovery Kids program ; the following year, , a child-oriented spin-off of the TLChome renovationreality showTrading Spaces joined the lineup. The new block came about amidst growing children's programming synergies between broadcast and cable television networks. Prior to the Discovery agreement, CBS had launched a Nickelodeon-branded block in 2000, while The WB had begun pooling programs from sister channelCartoon Network onto its Kids' WB lineup as part of a growing cross-promotion arrangement between the cable channel and the block; in addition, the same month that Discovery Kids on NBC debuted, ABC relaunched its Saturday morning block as ABC Kids, expanding upon a programming agreement established in 2001 with sister networkDisney Channel that later included select programming from Toon Disney. In September 2003, the block introduced educationally-oriented animated programs under the banner "Real Toons" – with two series, Kenny the Shark and Tutenstein; this marked the first time that NBC had aired animated series as part of its children's programming lineup since August 1992.
In March 2006, Discovery declined to renew its contract with NBC for its Saturday morning block, citing a desire to focus its children's programming efforts exclusively on the Discovery Kids cable channel; in May of that year, NBC and Ion Media Networks unveiled a joint venture with Corus Entertainment, Scholastic and Classic Media known as Qubo, which would aim to provide educational programming aimed at children between 4 and 8 years of age. The Qubo endeavor included a three-hour Saturday morning block on the network, which replaced Discovery Kids on NBC on September 9, 2006.
Programming
Although the Discovery Kids on NBC block regularly aired on Saturday mornings, affiliates in some parts of the country deferred certain programs within the lineup to Sunday morning time slots to accommodate locally produced programs or due to scheduling issues with regional or network sports broadcasts that start in time periods normally occupied by the block.